Tire pressure question

holderp · January 28, 2003

I have the 255/70R16's on my '03 2WD 1500 Sierra. I was getting ready to check the tire pressure the other day and the sticker on the door said 28psi front and 38psi on the rear. Is this right?? I did what I was told and now the fronts look too low. It came from the dealer with 42psi all around. I don't think that I have had a vehicle asking for this low of a pressure on a tire. My last three vehicles, including my S10, required 35psi all around. Can anybody shed any light on this?

Markeaux · January 28, 2003

I have heard the factory puts 42 (well at least for P tires) all around for shipping but the dealer is supposed to adjust them per the door placard. I, too, have had multiple new vehicles (cars, suv's) delivered with 42 whereas the placard said way lower ... and I'm sure many of the test vehicles on the lot still have way too much psi which causes many ppl to balk at how rough they ride (especially cars with lower profile tires). I have even had the dealer svc dept put 42 in during an oil change whereas the placard said 30 (that was on a 98 Z28 and 42 made it feel like there was no suspension at all)!

Anyway, as always, radials are still supposed to pooch a little or "look low" (but of course not actually BE low). I would go with the psi on the placard then if you absolutely can't stand it adjust 2 lbs up or down at a time and test, etc - or maybe at least reduce the rear a few psi if not hauling.

asepgrad98 · January 29, 2003

you have to realize GM does not warranty the tires. You will get many more miles out of them if you set them at 35psi. Dont forget to add 3psi if the tires are "hot" when you check them.

mnstrmdnss · January 29, 2003

i sell and install tires everyday, and the placard on the door panel is the right psi rating. the vehicle manufacter(chevy, in this case), reccomends this psi for the tire size it was designed for, in this case, 255/70 16's, most importantly, tire wear. too much pressure will cause the center of the tire to wear faster than the edges, too little psi will cause the outside edges of the tire to wear faster. as long as you stick with the same tire size that is on the placard, despite tire company or even "p" or "Lt" rated, go with the psi rating on the placard, dont second guess the manufacturer. they know what their doing.

asepgrad98 · January 29, 2003

dont second guess the manufacturer. they know what their doing.

Lets not forget Ford told people to put 26psi in the Explorer and we all know how that turned out. The Firestones were fine it was the low air presser that killed many people. The proof of this is the fact that the replacement Continential SUV tire had a higher failure rate than the Firestones.

Markeaux · January 29, 2003

dont second guess the manufacturer. they know what their doing.

Lets not forget Ford told people to put 26psi in the Explorer and we all know how that turned out. The Firestones were fine it was the low air presser that killed many people. The proof of this is the fact that the replacement Continential SUV tire had a higher failure rate than the Firestones.

But there were still many thousands of others running the same 26 that had no problems at all, my 93 Explorer included. It is my belief that it was a combination of factors but was mainly due to poor/cheap tire construction, and not only that for at least one tire type it was found to be more of a problem as specific plants (where they presumably used even cheaper/lower quality processes).

There are certainly many tire mfgr's that make poor/cheap tires. And a poor/cheap tire can fail at heat/abuse levels much lower than a higher quality tire. The Firestone 500 fiasco of the 70's was almost ubelieveable. All 5 of the oem 500's that came on my gf's Camaro blew out in the first year she had the car ... 3 while I was driving. Amazingly cheap tires, they were failing all over the country.

I also believe that many vehicle owners rarely check their tires for proper pressure and in the case of the Explorer there was probably a large amount of tires inflated even below 26. 6 months ago an Explorer with 4 adults passed me while accelerating on an entrance ramp to a 65mph freeway AND THE RIGHT REAR TIRE WAS TOTALLY FLAT! They did not even know it. I tried to catch up to them but I was in the wrong lane and they sped away. Sheesh!

Anyway, for the last 20 years or so I have mostly been using higher quality/speed-rated tires on my vehicles and have never had a tire failure - flats yes, but no blowouts, separations, etc. And yes on some of those vehicles I have run a few pounds less than depicted on the door placard for better handling and/or ride quality. (But I never ran less than the 26 on the 93 Explorer, I think that was an absolute minimum. Ford did issue a replacement placard depicting 30, but with that pressure the vehicle skitters and twitches around terribly on washboard surfaces so a drop down to 28 is overall better - the Explorer suspension pretty much just plain sucks especially in the early models with the higher rate spring/shock package).

BlueRado · January 29, 2003

My experience is that the door placard tends toward underinflation, and I've always assumed it's really for ride quality, which is true, so long as the pressure isn't set too low, ie - Firestone/Exploder issue.

I think asepgrad has it right, but I go by 3 criteria: 1) what does the tire sidewall say as max cold, or just max, 2) how is the wear, and 3) adjust it up, but not over max if I'm towing or hauling a load. Another poster mentioned adjusting up or down incrementally - that's what you'll need to do. For example, w/ my Duelers, the sidewall says 50 psi max cold, so I run 42 psi in front and 40 in back unloaded cold, then bump each up if I'm hauling ot towing a load, to say, 46 front, 44 back, or more if heavy loads.

Hope this helps.

Markeaux · January 29, 2003

I also noticed on the Michelin LTX's (that I put on the 93 Exploder) that is says something like "50max at xxxx lbs" (the vehicle is not here at the moment so I can't verify the exact numbers) ... so that does not mean 50max "always", but rather the weight of the vehicle/axle needs to be taken into account and then calculated/compared with the "xxxx lbs" on the tire sidewall (I suppose some ratio can be derived).

holderp · January 29, 2003

I'm going to do what I normally do. I add 2lbs. to the mfgrs. pressure.

I was just concerned about the low amount for the front. I have never had a vehicle that recommended this low of a pressure on a tire.

Thanks for the input.

ClipperSkipper · January 30, 2003

We've been inflating tires right up to max these days with the cold weather, you can't go wrong by inflating the tires to their maximum recommended operating pressure.

Have a great one!

99silveradoz71 · January 30, 2003

ran 37 in my stock Wilderness AT's and got almost 38k out of them. Probably could've kept them longer, but I wanted new rubber before the winter.

k1500chevy97 · January 30, 2003

I am running 35 psi all around right now

during the summer i will be up about 50

Redapple · February 3, 2003

I ran 45psi in my firestones, and am running 50 in my goodyears. got 40k from the firestones, and currently have almost 10k on the goodyears. no problems at all.

Bill :thumb: