Tire Pressure

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On my Suburban ever since the tire shop installed my new tires they looked very low, in fact two people have pointed it out to me. I checked the pressure and it was about 35, which is what the door sticker says. However, I increased it to 40 all the way around, and they look a lot better, the ride quality is definitely firmer, but I like that the whole truck feels less squishy now. I did notice that on the highway the steering feels much lighter - not sure if that is good or bad. I'm curious what the downside is of having the tire pressure this high? On the tires it says 51PSI is the max so I'm not too concerned about blowing a tire but just in terms of handling and wear...
 
A little harsher ride, tires may wear a little faster in the middle are the only small downsides I can think of. It's what I do.
 
If you replaced P-rated tires with LT tires, you (well, the tires) probably need you to deviate upward from the door-panel sticker's information.
 
Originally Posted By: khittner
If you replaced P-rated tires with LT tires, you (well, the tires) probably need you to deviate upward from the door-panel sticker's information.


I ended up going with P rated tires again because they were much cheaper, though I would have preferred LT rated tires. They are one size large (265 vs 245) than stock. I initially wanted to increase the tire pressure to improve fuel economy, but the stiffer ride quality is nice, especially because my shocks are quite worn.
 
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I always run my tires around 3-5 psi higher than the door and haven't had any negative affects. I think it helps the tire actually last a little longer from less flexing and heat. I've never had a tire wear in the middle from too much air. It seems you would need to put close to the max pressure listed on the sidewall or higher to do that.
 
Originally Posted By: racin4ds
Harsher ride and sometimes even better MPG's is the result. 5psi isn't enough to wear the centers on a tire.


Thanks, that's exactly what I was hoping for.
 
Originally Posted By: dogememe
Originally Posted By: khittner
If you replaced P-rated tires with LT tires, you (well, the tires) probably need you to deviate upward from the door-panel sticker's information.


I ended up going with P rated tires again because they were much cheaper, though I would have preferred LT rated tires. They are one size large (265 vs 245) than stock. I initially wanted to increase the tire pressure to improve fuel economy, but the stiffer ride quality is nice, especially because my shocks are quite worn.


Just my experience, but if you went UP in size on a P rated tire, then you actually need LESS pressure in the tire for even tread wear.

I had a vehicle where the stock tire size was 255/70, and somehow ended up with 285/65 tires. Running the 285s at the same pressure as the 255s resulted in the center tread wearing out way too quick.
 
I run 42 psi cold on my truck, Michelin & BFG tires. 32 is what the decal says. Tires wear great & the ride is a little more firm but it doesn’t bother me
 
So sidewall bulge is what folks are seeing and saying when they comment about tires looking under-inflated ... But the 265's may be right at the door pressure.

IF the read width is wider than the rim width, you do not want to run higher pressures. The sidewall bulge may just be because of the way the tire is constructed.

Look closely at the outer edges after you have driven on a mixed surface. Something like gravel to color the tread and then asphalt into town or something. If you see much edge tread not showing contact with the asphalt, you need to lower the pressures.

And remember that pressures need to be set based on load. A suburban with a A/C equipped 454 and nothing in the back is going to need different pressure front-back than one with a small block and all you tools in the back.

the trick is to get some wear on the outer edges, even if most of the wear is actually going on in the centers. And they need to look even all the way around. Once you have established the best wear pattern, measure the top rim lip to the ground (just a handy reference point) and set all four to that ride height. They will wear evenly and offer best traction and handling
smile.gif
 
Originally Posted By: BrocLuno
...... IF the tread width is wider than the rim width, you do not want to run higher pressures. ......


This is tantalizingly close.

The stock wheels on a 1997 Suburban are 6.5" and the minimum allowable rim width on a P265/75R16 is 7". The bulge is coming from using a rim that is too narrow and it is causing the tire to arch.

And adding pressure is making the situation worse.

At the stock 35 psi, the situation is that the P265 tire is more likely to wear in the center, and tend to follow the ruts in the road and be sensitive to crosswinds. Plus there may be some traction issues.

At 40 psi the situation is worse, but better for fuel economy.
 
Originally Posted By: czbrian
I always run my tires around 3-5 psi higher than the door and haven't had any negative affects. I think it helps the tire actually last a little longer from less flexing and heat. I've never had a tire wear in the middle from too much air. It seems you would need to put close to the max pressure listed on the sidewall or higher to do that.


I would have to agree. The door sticker on my new Toyota lists the tire pressure at 35 PSI. The tire itself has a max. pressure listed at 51 PSI on the sidewall. The car was delivered at 40 PSI. I run right around 41 PSI.
 
I always go around 3 psi higher over door placard for normal driving. If towing, I usually go up 5 psi... This has always given me even tire wear.
 
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Originally Posted By: CapriRacer
Originally Posted By: BrocLuno
...... IF the tread width is wider than the rim width, you do not want to run higher pressures. ......


This is tantalizingly close.

The stock wheels on a 1997 Suburban are 6.5" and the minimum allowable rim width on a P265/75R16 is 7". The bulge is coming from using a rim that is too narrow and it is causing the tire to arch.

And adding pressure is making the situation worse.

At the stock 35 psi, the situation is that the P265 tire is more likely to wear in the center, and tend to follow the ruts in the road and be sensitive to crosswinds. Plus there may be some traction issues.

At 40 psi the situation is worse, but better for fuel economy.


Didn't the Z71 Silverado trucks of the same body style come with the 265 tires stock with the same rims?
 
Just an FYI.

My new Hyundai SantaFe has TPM's that give a digital read out of each tire's pressure. I have checked the accuracy with a known tire gage.

I inflated the tires to 35 psi all around, on a cool 50 deg morning. The following weekend, we were over in eastern WA where is was sunny and hot. I noticed that just sitting in the sun, the display would indicate 38-39 psi, and driving on the interstate, it reached 42 psi all around. Maximum pressure per the sidewall is 44. So you may want to leave some room for temperature fluctuation.
 
Originally Posted By: Brigadier
Just an FYI.

My new Hyundai SantaFe has TPM's that give a digital read out of each tire's pressure. I have checked the accuracy with a known tire gage.

I inflated the tires to 35 psi all around, on a cool 50 deg morning. The following weekend, we were over in eastern WA where is was sunny and hot. I noticed that just sitting in the sun, the display would indicate 38-39 psi, and driving on the interstate, it reached 42 psi all around. Maximum pressure per the sidewall is 44. So you may want to leave some room for temperature fluctuation.
44 psi max cold, so 9 pounds lower than the max.
 
Originally Posted By: dogememe
Originally Posted By: CapriRacer
Originally Posted By: BrocLuno
...... IF the tread width is wider than the rim width, you do not want to run higher pressures. ......


This is tantalizingly close.

The stock wheels on a 1997 Suburban are 6.5" and the minimum allowable rim width on a P265/75R16 is 7". The bulge is coming from using a rim that is too narrow and it is causing the tire to arch.

And adding pressure is making the situation worse.

At the stock 35 psi, the situation is that the P265 tire is more likely to wear in the center, and tend to follow the ruts in the road and be sensitive to crosswinds. Plus there may be some traction issues.

At 40 psi the situation is worse, but better for fuel economy.


Didn't the Z71 Silverado trucks of the same body style come with the 265 tires stock with the same rims?


No. According to Tire Guides, the Silverado's with P265's had 7" wheels.
 
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