BodybyFisher Posted May 1, 2008 Report Share Posted May 1, 2008 Yesterday, I had to take a 260 mile trip to Manaloken, NJ. With gas prices skyrocketing, I decided to run my tires hard, so I put 37 cold in the front and 35 cold in the rear. I immediately felt the car moved easier, and found that with the 'usual' gas pedal pressure I was flying. During the trip with mixed driving, I averaged 51 MPH and got 23.3 MPG, which I thought was pretty good given my historical performance. I will admit that I did not push it, but I was not driving like grandpa either, my speed never exceeded 70. Be careful NOT to exceed the MAX air pressure on the side walls! 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...
jking220 Posted May 1, 2008 Report Share Posted May 1, 2008 I wish I could run my tires that hard... My TPS goes off if the tires hit 36 or 37, so if I have them over 32 or 33 cold, the TPS goes off when they warm up. Jonah Link to comment Share on other sites More sharing options...
BodybyFisher Posted May 1, 2008 Author Report Share Posted May 1, 2008 I wish I could run my tires that hard... My TPS goes off if the tires hit 36 or 37, so if I have them over 32 or 33 cold, the TPS goes off when they warm up. When the TPS was designed the gas prices were < $2.00 per gallon, run them hard and IGNORE that message! 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...
adallak Posted May 1, 2008 Report Share Posted May 1, 2008 Yep, the tire pressure and the wear of tires affect fuel economy drastically! The saddest thing in life is wasted talent Link to comment Share on other sites More sharing options...
Texas Jim Posted May 1, 2008 Report Share Posted May 1, 2008 I have mine at 34 front... 32 rear... cold. Any more than THAT... and it rides like an old wagon without any springs. Mine has 50 series tires not 60 or 70 series. Makes the ride a little rougher. When they warm up... they are around 36/37 front ... 34/35 rear. My TPMS goes off at 40 psi. Only had it go off once. Middle of july .... curvy road... in a hurry. Built up a little extra heat. Link to comment Share on other sites More sharing options...
JohnnyG Posted May 2, 2008 Report Share Posted May 2, 2008 Hmmm, that's something I haven't thought of. The TPS actually goes off when the pressure exceeds 40? Mine hit 37-39 easily, even at moderate 70° temps. Summer driving might get interesting. Running 35 cold on all 4. Never underestimate the amount of a persons greed. Link to comment Share on other sites More sharing options...
BodybyFisher Posted May 2, 2008 Author Report Share Posted May 2, 2008 I have mine at 34 front... 32 rear... cold. Any more than THAT... and it rides like an old wagon without any springs. Mine has 50 series tires not 60 or 70 series. Makes the ride a little rougher. When they warm up... they are around 36/37 front ... 34/35 rear. My TPMS goes off at 40 psi. Only had it go off once. Middle of july .... curvy road... in a hurry. Built up a little extra heat. You crack me to Texas, , I would expect no less! I have 65 series, and with 37/35 the ride is not noticibly inferior, but the handling is tighter. Keep in mind that they took SEARAY off the side of my 96 and put DEVILLE on it, its a baby coach.... Thanks.. 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...
BodybyFisher Posted May 2, 2008 Author Report Share Posted May 2, 2008 Hmmm, that's something I haven't thought of. The TPS actually goes off when the pressure exceeds 40? Mine hit 37-39 easily, even at moderate 70° temps. Summer driving might get interesting. Running 35 cold on all 4. Johnny, do they have a front/rear difference in air pressure on the tire pressure lable on your car? I tend to keep that stagger as using the same front and rear can cause under steer especially in the rain. I did a quick search and found this, you might want to experiment a little. PS, I did not get that box out to you yet, soon.... Mike http://www.passatworld.com/forums/showthread.php?t=172050 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...
Texas Jim Posted May 2, 2008 Report Share Posted May 2, 2008 With a Tech II, you can adjust the pressure point they go off at. Mine has only went off one time in two years... so I didn't have it adjusted. My understanding is .... they are factory set to go off at ten pounds OVER or UNDER the factory recommended pressure. I could be wrong... someone correct me if I am. I sometimes periodically check the pressure as I drive. Just to make sure all is right with the world. Would not be a good thing to be running long distance with a low tire. Link to comment Share on other sites More sharing options...
jking220 Posted May 2, 2008 Report Share Posted May 2, 2008 It appears I was wrong... my FSM says it will warn you if it is below 24 or above 39... I could swear it has warned me at 37, but I could be wrong. I will take them up to 35 once I get my new tires and see what happens. Jonah Link to comment Share on other sites More sharing options...
BodybyFisher Posted May 2, 2008 Author Report Share Posted May 2, 2008 It appears I was wrong... my FSM says it will warn you if it is below 24 or above 39... I could swear it has warned me at 37, but I could be wrong. I will take them up to 35 once I get my new tires and see what happens. Are those Z rated tires on your STS? Definately report back your results, thx 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...
jking220 Posted May 2, 2008 Report Share Posted May 2, 2008 Are those Z rated tires on your STS? Definately report back your results, thx Nope... only H rated... 130 top speed. The old 99 STS we had was Z rated... that was fun. I am going to look at apartments tonight, so I will take the rears up to 35 and see what I get. Im nervous taking the fronts up to 35 because I have a screw in one of them, and I dont want it to blow out. Jonah Link to comment Share on other sites More sharing options...
Texas Jim Posted May 2, 2008 Report Share Posted May 2, 2008 Im nervous taking the fronts up to 35 because I have a screw in one of them, and I dont want it to blow out. Get it fixed. Don't let them PLUG it. Take the tire off of the wheel and PATCH it on the inside. Have the tire guy mark the tire at the valve stem and put it back on in the same position and it won't even have to be re-balanced. Link to comment Share on other sites More sharing options...
jking220 Posted May 2, 2008 Report Share Posted May 2, 2008 Get it fixed. Don't let them PLUG it. Take the tire off of the wheel and PATCH it on the inside. Have the tire guy mark the tire at the valve stem and put it back on in the same position and it won't even have to be re-balanced. Im putting it off because it holds air pretty good, and I just ordered new Michelins all the way around. I cant wait to get them mounted up and RFB'ed. The tires that are on it now are 80K mile tires and hard as a rock. They are M&S's too, so I cant wait for the quiet, smooth ride when I get the Michelins on there. Jonah Link to comment Share on other sites More sharing options...
Texas Jim Posted May 2, 2008 Report Share Posted May 2, 2008 Im putting it off because it holds air pretty good, and I just ordered new Michelins all the way around. I cant wait to get them mounted up and RFB'ed. The tires that are on it now are 80K mile tires and hard as a rock. They are M&S's too, so I cant wait for the quiet, smooth ride when I get the Michelins on there. Understand THAT. If it is holding air ok... and you are putting new tires on it... no need to spend money on THAT tire. Link to comment Share on other sites More sharing options...
Ed Hall Posted May 2, 2008 Report Share Posted May 2, 2008 I run both fronts and backs at the maximum pressure which is 44 psi. It rides pretty hard but I does allow me to get a bit over 20 mpg on the freeways. I get the best fuel economy when I limit my speed to 55 mph. I get about 23 mpg at that speed and never using more than 1/4 throttle and slowing down when going up hills. At 70, I'm down to 18 mpg. Last week, I went to the gas station to fill up and it hit the limit of $75 credit card limit and the gas tank was still not full. On my Suburban, it now costs over $150 to fill her up with diesel. Link to comment Share on other sites More sharing options...
KHE Posted May 2, 2008 Report Share Posted May 2, 2008 Be sure to check the tire wear pattern when running them at higher pressures. They may start to wear faster in the center of the tire vs. the edges. Kevin '93 Fleetwood Brougham '05 Deville '04 Deville 2013 Silverado Z71 Link to comment Share on other sites More sharing options...
MAC Posted May 2, 2008 Report Share Posted May 2, 2008 Sometimes I pump tires up until they have 40. Is this OK? I think I heard that too much can be bad for gas mileage--is this true? Link to comment Share on other sites More sharing options...
BodybyFisher Posted May 2, 2008 Author Report Share Posted May 2, 2008 Sometimes I pump tires up until they have 40. Is this OK? I think I heard that too much can be bad for gas mileage--is this true? 40 cold translates to a lot more HOT.... The side of MY Michelin Symmetry says max pressure 44, so be careful with that. If you over inflate, as KHE stated the CENTER of the tire will wear more as it bulges out. Conversely under inflating the tire causes the edges to wear. 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...
JohnnyG Posted May 5, 2008 Report Share Posted May 5, 2008 Sorry for the late reply, been working too much. No Body, there is no stagger on this model, it calls for 30 all around. I suppose I could live with that, but I'm coming off an STS that ran 35 all around, so the ride is still A BIG IMPROVEMENT, and not too noticeable to me. If the pressure sensor goes off this summer, I might back 'er down a pound,..maybe pound and a half I sometimes periodically check the pressure as I drive. Just to make sure all is right with the world. And I thought I was the only one.... Ed Hall! 44 all the way around? Check with Cardio Doc, I think he had a set of solid steel wheels that have the same bolt pattern as your car. Honestly....just steel, no rubber at all! GreaT FUEL ECONOMY OR THEY WOULDN'T PUT THEM ON TRAINS! No need to worry about flats either BTW. Just kidding of course, thats a bit too high. I wouldn't go over 36 in the summer for safety's sake. Heat really changes a tire's pressure. I've just learned that recently! Never underestimate the amount of a persons greed. Link to comment Share on other sites More sharing options...
Ed Hall Posted May 6, 2008 Report Share Posted May 6, 2008 Yes, I run 44 psi front and back since my tires are designed to run at such pressures. With it costing nearly $100 for fill up, I also don't drive much over 55 mph. With high pressure in my tires and lower speeds, I am now getting 24 mpg on the freeway. Link to comment Share on other sites More sharing options...
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