TDK Posted June 9, 2008 Report Share Posted June 9, 2008 Dear All, My favorite youngest son told me one of the '99 Caddy tires looked low. He set out the air compressor I bought him, and I started to check them with my El Cheapo dial gauge. It is without a hold-button but it is chrome-plated after all. I then noted his fancy one on his bench. He having raced his car with special rims, tires and all - I thought - hey why not use the best gauge here. His was a dial-type, (bourdon-tube like mine), but much larger, heavier and with a hold-button. To my suprise, all the tires were 35-36psig, (cold). I decided to actually read the door label and adjust themn to 30psig all around. I checked my gauge and it read about 24psig (just before it went in the trash). On the way home, the Big White Dog, got a respectable 25.1 average over 150-miles with the cruise set at 82-mph (average = 78.2-mph). There were about 20-miles of 65-mph limit and 55-mph road construction one lane as well as a few romps above 90. Needless to say, the car was quieter and rode smoother as well. I suppose I might keep the tires at 30 psig. I also need to find the electronic one I have and do some more comparisons, perhaps with a"dead-weight" tester at work. So, what is your favorite type of tire gauge? 1. The classic Pencil/stick 2. Dial (with or w/o hold buttom) 3. Hand-held electronic 4. The car has tire pressure indicators, but I check anyway. 5. The car has indicators, I paid for 'em and trust 'em. 6. Local valve stem color indicators. 7. What's tire pressue? Bruce, please feel free to change this into a Poll, I forgot how. Thanks Add power to leave problems behind. Most braking is just - poor planning. Link to comment Share on other sites More sharing options...
JimD Posted June 9, 2008 Report Share Posted June 9, 2008 The tire pressure guage I use is a Bourdon tube type with a short rubber hose and branded for Cabella's (as if Cabella's makes any difference). I have no way to measure the tolerances and accuracy of the various means of tire air pressure measurement. For me, the bottom line is the balance/compromise in the tire life vs ride comfort vs handling vs fuel economy vs safety calculus. For me, tire life and safety considerations are first and foremost. Most tire pressure adjustments I make are based on tread depth measurements at the middle of the tread compared to the outer edges. If the rubber is not wearing evenly, I make a pressure adjustment. The current set of Michelins on my '98 have given me 70,000 miles of service. They are very close to the end of the safety factor. The absolute air pressure reading is not critical (due to the unknown accuracy of pressure guages); what is more important is you use the same guage every time you check your tire pressure. Jim Drive your car. Use your cell phone. CHOOSE ONE ! Link to comment Share on other sites More sharing options...
catmendo Posted June 9, 2008 Report Share Posted June 9, 2008 [so, what is your favorite type of tire gauge? 1. The classic Pencil/stick 2. Dial (with or w/o hold button) 3. Hand-held electronic 4. The car has tire pressure indicators, but I check anyway. 5. The car has indicators, I paid for 'em and trust 'em. 6. Local valve stem color indicators. 7. What's tire pressure? ------------------------------------------------------------------------------------------------------------------------------- "Most tire pressure adjustments I make are based on tread depth measurements at the middle of the tread compared to the outer edges" quote from JimD ...et al .... i heartily agree with what JimD said, and if you use his style of thinking it is done best and easiest on brand new tires when they still have all those little rubber hair things on them ... you just watch how they are wearing while they are wearing away (thanks Ed S.) ... i also like to go by what the tire says on it about correct pressure for that kind of tire ... as for gauges a couple of months ago i was filling a tire on my pops truck and had his three gauges ... one cheap dial gauge and two pencil ones ... i used the first one and put air in, gauge said not enough, put more in, gauge still said not enough, put more in until it said 35 PSI ??? i have been playing on cars, a good thirty years and i knew in my head, that i had put a lot of air in that tire, so i rounded up all the other gauges that i had on hand... pop's other two ... three from the family golf course and the two from in the trunk of my car(i have several more) ... i checked the air, in the tire, that i filled with the first gauge, with a second gauge and it read 60 PSI ??? used another one and took the tire down to 35 i ended up throwing away all the gauges that didn't agree on 35PSI which was about half of them ... my favorite gauge is one of the nice ones like at a gas station with the brass ruler looking thing that slides out like the one that i have on my compressor and remember guys whether it is a pencil type or a nice one like mine if it has a sliding measuring stick thingy on it you must keep it oiled or it will not be correct in its readings ... if you want to buy you son a nice gift then buy him one like mine ,they don't cost much ... i got mine from Lowes ... i just looked and mine is an Amflo 150 ... if i remember right it was part of a kit that had a bunch of other cool things with it like air blower thing and so such ... <a href="http://www.plews-edelmann.com/index.cfm?location_id=3790" target="_blank">http://www.plews-edelmann.com/index.cfm?location_id=3790</a> Lane Link to comment Share on other sites More sharing options...
catmendo Posted June 9, 2008 Report Share Posted June 9, 2008 [ 4. The car has tire pressure indicators, but I check anyway. 5. The car has indicators, I paid for 'em and trust 'em ----------------------------------------------------------------------------------------------------- sorry, but are you talking about the little junk things that you buy after market to replace your valve stem caps with, that have a built in little slider gauge ??? if so, all you have done, is replace something that was added, as a secondary measure to keep air from leaking from the valve stem ... and it defeats the purpose of the cap ... if so, then take them all off, and put them on different wheels and see if they, still read the same things and when they don't , throw them all away ... after market stuff, is a lot like, fancy fishing lures, that are made to attract the fisherman more so than the fish ... please tell me that i am wrong here and i will be more than happy to say , my bad ... Lane Link to comment Share on other sites More sharing options...
JasonA Posted June 9, 2008 Report Share Posted June 9, 2008 I like the ones with dials. I've found a lot of variability in the pencil/slide gauges. Probably due to the lubrication issue catmendo mentioned above. Jason(2001 STS, White Diamond) "When you turn your car on...does it return the favor?" Link to comment Share on other sites More sharing options...
TDK Posted June 9, 2008 Author Report Share Posted June 9, 2008 [ 4. The car has tire pressure indicators, but I check anyway. 5. The car has indicators, I paid for 'em and trust 'em ----------------------------------------------------------------------------------------------------- sorry, but are you talking about the little junk things that you buy after market to replace your valve stem caps with, that have a built in little slider gauge ??? if so, all you have done, is replace something that was added, as a secondary measure to keep air from leaking from the valve stem ... and it defeats the purpose of the cap ... if so, then take them all off, and put them on different wheels and see if they, still read the same things and when they don't , throw them all away ... after market stuff, is a lot like, fancy fishing lures, that are made to attract the fisherman more so than the fish ... please tell me that i am wrong here and i will be more than happy to say , my bad ... Lane Catmendo, What I meant in these two cases were the electronic options on some newer Cadillacs and other vehicles. These devices measure the tire pressue electronically at each wheel while rolling, etc - and report back to the vehicle's computer, which issues warnings etc. I believe there are other vehicle systems that calculate/predict tire pressure "issues" based on sensed differences in the powertrain and/or suspension system. The valve stem color indicators (which I don't use and agree with you), #6 selection, may have been what you were referring to in the fishing lure note. Thanks, Add power to leave problems behind. Most braking is just - poor planning. Link to comment Share on other sites More sharing options...
BodybyFisher Posted June 9, 2008 Report Share Posted June 9, 2008 I have grown to HATE the tire pressure gages that look like a PEN, and the indicator pops out of it, they are SO inaccurate to me especially the cheap ones. I have come to like the dial type it appears much more accurate. This is what mine looks like but its of much better quality than this one Pre-1995 - DTC codes OBD1 >> 1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/ Cadillac History & Specifications Year by Year http://www.motorera.com/cadillac/index.htm Link to comment Share on other sites More sharing options...
catmendo Posted June 9, 2008 Report Share Posted June 9, 2008 What I meant in these two cases were the electronic options on some newer Cadillacs and other vehicles. These devices measure the tire pressue electronically at each wheel while rolling, etc - and report back to the vehicle's computer, which issues warnings etc. -------------------------------------------------------------------------------------------------------------------------------- "after market stuff, is a lot like, fancy fishing lures, that are made to attract the fisherman more so than the fish ..." please tell me, that i am wrong here and i will be more than happy to say , my bad ..." good deal ... and i am happy to say ... my bad ... ----------------------------------------------------------------------------------------------------------------------------------- also ... Jason, i think that i may owe you one too ... so, my bad ... sorry, if we rubbed each other the wrong way ... CMD Link to comment Share on other sites More sharing options...
JasonA Posted June 9, 2008 Report Share Posted June 9, 2008 also ... Jason, i think that i may owe you one too ... so, my bad ... sorry, if we rubbed each other the wrong way ... No hard feelings. We're all here to learn and enjoy our cars. Jason(2001 STS, White Diamond) "When you turn your car on...does it return the favor?" Link to comment Share on other sites More sharing options...
catmendo Posted June 9, 2008 Report Share Posted June 9, 2008 " For me, tire life and safety considerations are first and foremost. Most tire pressure adjustments I make are based on tread depth measurements at the middle of the tread compared to the outer edges. If the rubber is not wearing evenly, I make a pressure adjustment. The current set of Michelins on my '98 have given me 70,000 miles of service. They are very close to the end of the safety factor." ---------------------------------------------------------------------------------------------------------------------------------- JimD ... since i can tell that you already know lots about watching tire wear , i am posting the following as a "little nickle knowledge" as my anthropology prof. use to say ... and if you took notes in his class and kept the nickle knowledge you would breeze his test ... to check the tread wear on your tires, take a penny and put it between the treads and if the tread does not reach ol' abe's head then it is time for new tires ... Link to comment Share on other sites More sharing options...
JasonA Posted June 9, 2008 Report Share Posted June 9, 2008 Like Jim, I also use a tread depth gauge. It also helps me to determine when a tire rotation is in order. I won't rotate the tires until there's a 1/32" difference in tread depth front-to-rear. If the tires start wearing a little feathered on the edges, I'll just rotate them side-to-side if there's not a big difference in tread depth. I prefer to replace tires at the 4-5/32" mark. Many are calling for an update to the coin test -- from the Penny test to the Quarter test. There's approximately 4/32" between the top of Washington's head and the edge of the quarter. It's the exact same as the Penny test -- but it's a little more conservative in that a tire change is indicated in the 4/32" tread depth neighborhood rather than 2/32". Here's a video from Tire Rack that shows the effective differences between new tires, and those with either 4/32" or 2/32" of tread depth: http://www.tirerack.com/videos/index.jsp?video=5 Jason(2001 STS, White Diamond) "When you turn your car on...does it return the favor?" Link to comment Share on other sites More sharing options...
catmendo Posted June 9, 2008 Report Share Posted June 9, 2008 Like Jim, I also use a tread depth gauge. It also helps me to determine when a tire rotation is in order. I won't rotate the tires until there's a 1/32" difference in tread depth front-to-rear. If the tires start wearing a little feathered on the edges, I'll just rotate them side-to-side if there's not a big difference in tread depth. I prefer to replace tires at the 4-5/32" mark. Many are calling for an update to the coin test -- from the Penny test to the Quarter test. There's approximately 4/32" between the top of Washington's head and the edge of the quarter. It's the exact same as the Penny test -- but it's a little more conservative in that a tire change is indicated in the 4/32" tread depth neighborhood rather than 2/32". Here's a video from Tire Rack that shows the effective differences between new tires, and those with either 4/32" or 2/32" of tread depth: http://www.tirerack.com/videos/index.jsp?video=5 cool, thanks Jason... and out of curiosity ... what are the hairy things on new tires called guys ??? tits ??? teats??? Link to comment Share on other sites More sharing options...
KHE Posted June 9, 2008 Report Share Posted June 9, 2008 Like Jim, I also use a tread depth gauge. It also helps me to determine when a tire rotation is in order. I won't rotate the tires until there's a 1/32" difference in tread depth front-to-rear. If the tires start wearing a little feathered on the edges, I'll just rotate them side-to-side if there's not a big difference in tread depth. I prefer to replace tires at the 4-5/32" mark. Many are calling for an update to the coin test -- from the Penny test to the Quarter test. There's approximately 4/32" between the top of Washington's head and the edge of the quarter. It's the exact same as the Penny test -- but it's a little more conservative in that a tire change is indicated in the 4/32" tread depth neighborhood rather than 2/32". Here's a video from Tire Rack that shows the effective differences between new tires, and those with either 4/32" or 2/32" of tread depth: <a href="http://www.tirerack.com/videos/index.jsp?video=5" target="_blank">http://www.tirerack.com/videos/index.jsp?video=5</a> cool, thanks Jason... and out of curiosity ... what are the hairy things on new tires called guys ??? tits ??? teats??? They are where the rubber is injected into the mold that creates the tire. I suppose the correct term would be gates but I always have called them tits.... Kevin '93 Fleetwood Brougham '05 Deville '04 Deville 2013 Silverado Z71 Link to comment Share on other sites More sharing options...
Ranger Posted June 10, 2008 Report Share Posted June 10, 2008 I have them all. I tend to use my latest acquisition, an electronic digital gauge. It reads to .5 psi and seems to be pretty accurate when compared to the TPI on the car. I run them at the advertised 30 psi. I like a smooth quiet ride. Link to comment Share on other sites More sharing options...
JohnnyG Posted June 10, 2008 Report Share Posted June 10, 2008 All of this is great stuff. I've always used "stick" gauges, since they can't be stressed or overloaded like the bourdon tube type gauges, but in the inflation ranges that we are talking about, that might be a bit unlikely. In retrospect, and since I have recently bought a car with the tire inflation sensors built in, I've found myself wondering a LOT about proper tire inflation. The built in tire pressue indicators tell me that my inflation pressures are all over the place! This is not to say that they aren't correct or anything, just that they indicate that the pressures vary.....A LOT! I have now reduced my tire pressures three times. The last two times were an attempt to make all of them agree when the car was parked overnight in a garage. ( keep in mind that outside ambient temps have been rising during this timeframe) This was easy to do, and soon had them all right on the money at 34 psi. The ambient temperature was maybe 75° or so. So I just went out to check them again, keep in mind maybe two short trips since I last checked them, and the car has been in the garage for 3 days.......but no air added or removed, and the two left tires are high, the two right ones still at 34. LF 35 psi, LR 37 psi! What gives? Ambient temperature today are 81°, so a six degree temp increase only affects two tires? This is all going by the tire pressure monitors built into the vehicle....I'm not even getting the tire gauge out. SOOOOO, my question is this, will a nitrogen fill make my tire pressures more stable in changing ambient temps? Never underestimate the amount of a persons greed. Link to comment Share on other sites More sharing options...
TDK Posted June 10, 2008 Author Report Share Posted June 10, 2008 Johnny G , et al, Following is a link about tire nitrogen. http://www.straightdope.com/columns/070216.html There is a LOT out there on the net - so like the Bible, you can find anything to support any opinion... What I wanted to mention about nitrogen, was that there is a significant safety issue concerning enclosed, poorly ventilated spaces. Obviously, there are huge differances when dealing with tires etc, but it is easy to conk out breathing nitrogen with no warning. A friend of mine died in an instrument building because a tiny nitrogen purge line leaked. Another guy working alongside me also fell over while we were sampling a reactor catalyst bed blanketed with nitrogen. He got a whiff of this colorless, odorous gas - which displaces oxygen in the lungs right now - while too close to the access port, fell over, but recovered. Back to the thread... I found and used my digital pressure gauge. It was within a pound of the dial type under the same conditions. It has a re-calibrate button and beeps three times when the pressure stabilizes. I'll take it to work and check its calibration anyway. Ultimately, even tire wear is certainly one of the most important reasons to check/adjust tire pressure, as JimD, Jason and others have wisely noted. Ride control is also a factor as well as mileage. All of these factors can take a differant order of importance for each person (or no importance at all). It seems the accuracy and repeatability of each type of gauge is far from being resolved - if that was ever an objective. If someone finds a study citing the differances, etc - please let us know! Oh yea. I forgot to mention the reason my FYS noted the tire profile difference may have been that the tire in question was a relatively new Mich-Harmony, as opposed to Mich-WX4's on the other 3 corners. And yes, it was on the passenger-rear, not the front to argue with the other type tire via the differential, etc. Thanks all, Add power to leave problems behind. Most braking is just - poor planning. Link to comment Share on other sites More sharing options...
Babydon Posted June 10, 2008 Report Share Posted June 10, 2008 My digital gauge reads way off what my car's indicators read - which should I go by??? ...or in other words, how do I know my indicators are working properly? Link to comment Share on other sites More sharing options...
TDK Posted June 10, 2008 Author Report Share Posted June 10, 2008 My digital gauge reads way off what my car's indicators read - which should I go by??? ...or in other words, how do I know my indicators are working properly? Babydon, Here is a VERY interesting link to how various electronic tire presure indicator systems work. <a href="http://en.wikipedia.org/wiki/Tire_pressure_monitoring_system" target="_blank">http://en.wikipedia.org/wiki/Tire_pressure_monitoring_system</a> Be advised that the link itself notes that its info inside has been disputed. The link notes that the technology is still developing and that issues like battery life, calibration, and safety/liability are still major concerns. The US has different laws that say Europe, so not all equipment can be used here. It seems none of the direct-measuring systems (with a pressure transmitter inside the tire), are trouble-free and the batteries last maybe 5-7years at best, less in sub-zero conditions. Actually, I'm rather surprised they work at all - considering all the vibration, heat, cold and "tire mechanics". The indirect monitoring systems do not use wheel-mounted pressure transmitter with batteries. They use existing suspension/wheel speed inputs for ABS systems to calculate differences in rotation speeds to predict which tire is out of range with others. This system can not tell you if all the tires are low, but only if one is significantly lower than the others. I don't know which specific kind of direct-measurement system Caddy uses. I think my wife's new Rabbit uses an indirect-measurement system. I can certainly see pros and cons with both systems. For example, if you simply want a system that alarms if a single tire is going flat before it completely fails, then the indirect system is fine. If you need a system that indicates each tire accurate to a few pounds pressure, then the direct systems are capable, but perhaps more service-intensive. Considering JohnnyG's comments regarding odd, erratic pressure indications from his on-board system, perhaps you are not alone? Personally, with what little I know... I would use JimD's and Jason's logic regarding tire wear - to determine if your tire pressures are too high or low for your vehicle and driving style. I would also use a digital pressure gauge with a calibration reset and a reading stabilization beep - to have them all at even pressure. If your vehicle is within warranty (or even if not, if you believe it to be important), you may want to show the dealer your comparative tire pressue readings - if the info shows the on-board indicators are defective. Good luck Add power to leave problems behind. Most braking is just - poor planning. Link to comment Share on other sites More sharing options...
catmendo Posted June 10, 2008 Report Share Posted June 10, 2008 TDK, i have spent the last hour reading many article on this link and to be honest ... i think, that there is more good common sense and knowledge going on, in this thread than much of what, i have been reading ... experience rules ... http://www.google.com/search?hl=en&rlz...ate&spell=1 i am now, going to hunt up something, that i posted a week or two ago, on this site and post it next ... it was on another thread here ... tie rod stuff ... Link to comment Share on other sites More sharing options...
catmendo Posted June 10, 2008 Report Share Posted June 10, 2008 i am now, going to hunt up something, that i posted a week or two ago, on this site and post it next ... it was on another thread here ... tie rod stuff ... ok, found it ... Ed S. is the one, that taught me how to watch how the tits wear, on new tires and to adjust accordingly for both proper tire pressure and toe in and toe out etc. ... ------------------------------------------------------------------------------------------------------------------------------ i agree with BBF, moog makes very good parts ... do you need a tie rod or just a tie rod end ??? i have replaced tie rod ends before and counted the number of threads on the adjustment and duplicated, the same on the new one and had no need to have an alignment, but if i was considering doing that, i would buy an ac-delco part ... i have a buddy, named Ed and he and i have done some crazy stuff together when it comes to fixing cars ... and when he worked for firestone, i saw him prove to his fellow workers that he could do a front end alignment, by look and feel better than, they could do with their machines and supposed specs. ... he once, found the front end problem, on one of my gal pals car in five seconds after three of the best shops in town looked at it and came up with all kind of stupid reasons why they could not align it the best front end shop in town said that someone had put the wrong tie rod on it ... he found the problem, laying on the ground, looking under the car while i turned the steering wheel ... they all had lifts and could not see that the steering box was torn away from its mounting on an uni-body fiat 128 spider ... that girl, could have been died, if it had broken all the way free while going down the highway ... a little plasma welding and it was fixed ... -------------------------------------------------------------------------------------------------------------------- sorry guys, if that was a little long, but it just seemed best to post the works ... Lane Link to comment Share on other sites More sharing options...
JohnnyG Posted June 11, 2008 Report Share Posted June 11, 2008 What I wanted to mention about nitrogen, was that there is a significant safety issue concerning enclosed, poorly ventilated spaces. Obviously, there are huge differances when dealing with tires etc, but it is easy to conk out breathing nitrogen with no warning. A friend of mine died in an instrument building because a tiny nitrogen purge line leaked. Another guy working alongside me also fell over while we were sampling a reactor catalyst bed blanketed with nitrogen. He got a whiff of this colorless, odorous gas - which displaces oxygen in the lungs right now - while too close to the access port, fell over, but recovered. Thanks for the info. The article does mention that the nitrogen content of the air we breathe is nearly 80%.. At work I've learned that as a result of that, our bodies do not "alarm" at the presence of excessive nitrogen in the air like it would with increased amounts of CO2 or other gasses. The link did have some good info, and turned on a light bulb for me. I'm giving up on the nitrogen idea since the article seemed to indicate that moisture content of the air in the tire has a greater effect on pressure vs. temperature changes. And I'm going to suggest that tire TEMPERATURE reading be incorporated into the next tire pressure monitors. That would do two things, it would provide early warning of excessively hot tire caused by factors other than low pressure, and would provide a "basis" for judging the expansion rate of the air in the tires, thereby allowing you to estimate if outside factors are affecting the inflation readings. Let's face it, if tire temperature differences in a closed garage can impact tire inflation readings by 3 degrees, what good is a tire gauge that reads to 1/2 pound? Do you make sure that the sun isn't shining on one of the tires before you check them? Never underestimate the amount of a persons greed. Link to comment Share on other sites More sharing options...
TDK Posted June 11, 2008 Author Report Share Posted June 11, 2008 JohnnyG, et al, OK then. It seems the major safety reason to check tire air pressure is to prevent loss of control, overheating and tire failure. The other major reasons to check tire air pressure are; tire-wear, fuel economy, but with many folks nowdays - comfort is riding last, (pun intended). All can agree that heating of the air inside a tire raises the pressure, (hence to check tire pressures cold). The amount of moisture in most compressed air maxes out around 5%, so as long as the tire guy doesn't slop too much water and slip-um around, then moisture (which affects all other constituant percentages), along with the; 78% nitrogen, a little less than 1% argon and the 21% or so of oxygen around us all - "may" not be a big contributer to causing problems with heat vs pressure correlations. In practicality, a very QC-specific tire-install procedure (to minimize water usage) would be difficult to administrate. However, it seems that a given vehicle's telemetry could use tire pressure-rise to predict tire temperature. This is where many note that nitrogen aids in with providing a consistent, minimal gas expansion ratio with heat, cooler running, less gas-molecule seepage/loss and more predictability. There are some other benefits, such as less oxidation to the tire and rim - but in order of importance, those benefits may be minimal at best. Following is an "elegant argument" proposing that using nitrogen can result in underinflation. Please be aware that the "logic" here is a bit crooked and needs to be followed slowly: We can all agree that passenger car tires were always and are now designed to use air to inflate. Passenger tire and passenger vehicle manufacturers design/select both the tires and car-suspensions - to anticipate tires heating up and the pressure rising perhaps 10-15psig under high speeds and loads. If nitrogen is used and the pressures do not rise as anticipated (as they would have with air), then at anticipated speed and loads, the nitrogen-filled tires are actually "underinflated" from a tire-profile and performance aspect. So, then why not increase the cold tire pressue if filled with nitrogen by 5-10 or even 15 psig then problem solved right?. Well in this case again using nitrogen, the tires will always be harder around town. In the case of air, the tires are softer in town because speeds and loads are less, so tires are cooler and therefore at less pressure. While air can be seen as a curse, it also self-adjusts to the higher speeds and loads, where nitrogen does not. It seems to me that although nitrogen in tires can certainly help with specific, focused applications, (like racing, taxis, busses, construction), it may not be as beneficial and appropriate for all American drivers. And while I plunked down a lot of pixels above, I don't think I answered anything! Perfect Political Prose! Best Regards, Add power to leave problems behind. Most braking is just - poor planning. Link to comment Share on other sites More sharing options...
catmendo Posted June 11, 2008 Report Share Posted June 11, 2008 JohnnyG, et al, OK then. It seems the major safety reason to check tire air pressure is to prevent loss of control, overheating and tire failure. The other major reasons to check tire air pressure are; tire-wear, fuel economy, but with many folks nowdays - comfort is riding last, (pun intended). All can agree that heating of the air inside a tire raises the pressure, (hence to check tire pressures cold). The amount of moisture in most compressed air maxes out around 5%, so as long as the tire guy doesn't slop too much water and slip-um around, then moisture (which affects all other constituant percentages), along with the; 78% nitrogen, a little less than 1% argon and the 21% or so of oxygen around us all - "may" not be a big contributer to causing problems with heat vs pressure correlations. In practicality, a very QC-specific tire-install procedure (to minimize water usage) would be difficult to administrate. However, it seems that a given vehicle's telemetry could use tire pressure-rise to predict tire temperature. --------------------------------------------------------------------------------------------------------------------------- wow TDK , great post and logic, and i am most impressed sir ... CMD Link to comment Share on other sites More sharing options...
Texas Jim Posted June 11, 2008 Report Share Posted June 11, 2008 The built in tire pressue indicators tell me that my inflation pressures are all over the place! This is not to say that they aren't correct or anything, just that they indicate that the pressures vary.....A LOT! I have now reduced my tire pressures three times. The last two times were an attempt to make all of them agree when the car was parked overnight in a garage. ( keep in mind that outside ambient temps have been rising during this timeframe) This was easy to do, and soon had them all right on the money at 34 psi. The ambient temperature was maybe 75° or so. So I just went out to check them again, keep in mind maybe two short trips since I last checked them, and the car has been in the garage for 3 days.......but no air added or removed, and the two left tires are high, the two right ones still at 34. LF 35 psi, LR 37 psi! What gives? Ambient temperature today are 81°, so a six degree temp increase only affects two tires? This is all going by the tire pressure monitors built into the vehicle....I'm not even getting the tire gauge out. SOOOOO, my question is this, will a nitrogen fill make my tire pressures more stable in changing ambient temps? It seems odd that your pressures vary so much. Mine don't vary NEARLY the extent that yours do. I have found that when I add or release a little air... in can take a couple of minutes before it shows on the TPMS. It took me awhile to figure THAT out. (like several WEEKS) I was adding air.... taking out air... and getting a little bit ticked, because it was never the same pressure .... later.... that it was when I added or removed air. I was using the TPMS for all of my readings. It is real close to what my gauge reads, so the gage stays in the glovebox. I have mine at 34 front and 31 rear. That seems to give me a pretty fair compromise on ride quality and handling. I have 34,000 on it and the tires are wearing pretty evenly all the way across the tread. On the highway, at 75/85, they will rise to 37 front and 34 rear ... plus or minus 1 psi. They will stay pretty consistent during an all day drive. My TPMS alerts at 40 psi and at 20 psi. Link to comment Share on other sites More sharing options...
JohnnyG Posted June 12, 2008 Report Share Posted June 12, 2008 It seems odd that your pressures vary so much. Mine don't vary NEARLY the extent that yours do. I have found that when I add or release a little air... in can take a couple of minutes before it shows on the TPMS. What I meant was that they seem to vary a lot with temperature. I adjusted the other day, after reading the first set of posts in this thread, to 34 all the way around. Checked them again before my last post, and they were still all at 34. Maybe there's a little break in period for the sensors or something like that.....I'll probably never know. Anyway, they seem to like 34 psi, and after reading your post, 37 on the open road seems just about perfect to me. So it's air for me, and the automatic self adjusting properties inherent to that air. I think I'll go change the air in my tires now!! SOooo, come winter, would nitrogen be a better choice TDK? I expect even wider temperature swings in the winter, particularly when I head the highway cruiser down toward Orlando way, sometime in say February! Never underestimate the amount of a persons greed. Link to comment Share on other sites More sharing options...
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