Well - I 'm back and I'm confused (tire pressure)

**dahnoo** · 06-15-2007, 06:46 PM

Hi all,

This is probably a really dumb question on my part (yeah - I know - there are no dumb questions). It concerns the tire pressure on my new truck (2007.5 Chevy Silvy 2500 Crew Cab Short Bed / Diesel). The back tires take about 18pounds PSI more than the fronts:

Left Front: 59 psi Right Front: 59 psi
Left Rear: 77 psi Right Rear: 76 psi

These readings are from the OnStar diagnostics

- which are confirmed by the door placard. I have yet to have a vehicle with these characteristics. And of course all tires are the same - which is even more confusing as I am not getting how a tire can perform properly with such a different tire pressure - and then get rotated and use a new pressure. Is it the nature of the rear axle? Thanks for the insights that you can give me.

Regards,
Dave N.

**TrailLeadr** · 06-15-2007, 07:53 PM

I believe it's for ride characteristics. Since there is a lighter load in the rear of the truck, they want to have tires perform the same as the front.

**Cableguy** · 06-15-2007, 08:52 PM

Icaramba! 77psi. must be some bouncy around town with nothing in back.

**dahnoo** · 06-15-2007, 09:00 PM

Thanks - but again, all the tires are the same - how can they perform as well at such a different pressure level? That's the part I'm not understanding. They are rated at Load Range "E" (80 PSI). Is that just the maximum that they can be inflated BUT they function as well when inflated at different levels depending on the needs of the truck?

Thanks,
Dave N.

**dahnoo** · 06-15-2007, 09:03 PM

Hi Cableguy - As a matter of fact - it is not so much bouncy as it is bumpy. You "really feel the road." But the placard does say to inflate to these pressures and the truck has the new tire pressure sensors and give a message to OnStar that all is well.

Thanks,
Dave N.

**Rumpamuro** · 06-22-2007, 05:30 PM

so that means you need to inflate/deflate the tires when u rotate them thats such a pain, 77 psi seems really high even if they are diff. i woulda thought like 50 front and like rear 55-60

**Ksteele** · 07-30-2007, 03:06 AM

I have 1500HD that had E rated tires till I replaced them. Pay attention to the rear tires if you never carry a load or tow. At near 80 PSI the center will wear out quicker that the outsides.

On my original tires I lowered the rear tire pressure to 65PSI and kept the fronts at 57PSI. Rotate every 3000 miles and adjust tire pressure. They will last longer and ride will be noticable better.

Remember if you tow or haul to adjust rear tires to load you will be putting on them.

I run Bridstone Revo's 285/75/16 now and I keep all four tires at 63PSI. Been tracking wear with depth gauge and just rotated for the first 3K and all is good. This is my second set and I love these tires. 85MPH in the Florida rain and the truck handles like a champ. At those speeds and with these tires it will sound llike pressure washers going off in your fender wells and I kick up a roster tail behind me. LOL

**CaJuN625** · 08-03-2007, 02:31 PM

The backs should have LESS pressure because there's less weight back there. The more weight, the more the tires will bulge, so the more air they need to reduce sidewall flex.

Remember the Firestone ordeal? The tires weren't properly inflated to support the vehicle weight and the tires delaminated from the heat.

**mhgoldwing** · 08-22-2007, 05:34 PM

but I tend to follow the mfg. recommendations. They didn't grab those numbers out of thin air. Tires must interact with chassis and suspension components plus load, speed, temp., etc.

My new 07 Burb 4x4 recommends 30 psi all around. Tires are rated to 55 max psi. After driving a hundred miles at the factory pressure, I increased all tires to 35 psi for better handling and fuel economy.

I did note that the owners manual stated that the pressures on the door placard are the "minimum" pressure required to support max load.

The pressures recommended on your truck may have to do with it being a crew cab. Dunno.

**Steve** · 08-22-2007, 07:11 PM

I agree, the mfg. has come up with an idea for how much trucks are used and they have the tire pressure listed for a reason for the stock tires. Toes the 2007 in question have the tire pressure monitoring on the DIC? I know that OnStar was listed. I'm driving a 2007 Silverado this week and it all shows up in the DIC, but it's a 1500 so the numbers are 32 in the front and a bit higher in the rear.