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Tire Pressure

W

wooly

New Member
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Location
Ottawa, Canada
I have recently bought a 2007 Classic Sierra 2500HD. The truck came with new Cooper ATR 265/75 R16's

I checked the pressures today and it 50 PSI all round. On the sidewall of the tire it says max load is xxx kg at 50PSI.

The door pillar gives pressure data for 245/75 R16's as 55PSI front and 80 PSI rear.

What pressure should be in the tyres?

Thanks

Wooly
 
50 PSI is a good number. I believe the specs on the door for the 245's are for towing. Regardless, 80PSI is a lot.
 
Thanks for the replies. If I am towing a 5th wheel with about 1900lb pin weight should I keep the rears at 50, or increase it, if so what should they be?

Wooly
 
I had a question about this too. I'm running 285's @ 65psi as it says on the side of the tire. Given that its on the stock rim, i think the tire may be wearing a little more in the center, will dropping the psi to about 55 or 60 help me get a more even wear?
 
wooly said:
I have recently bought a 2007 Classic Sierra 2500HD. The truck came with new Cooper ATR 265/75 R16's

I checked the pressures today and it 50 PSI all round. On the sidewall of the tire it says max load is xxx kg at 50PSI.

The door pillar gives pressure data for 245/75 R16's as 55PSI front and 80 PSI rear.

What pressure should be in the tyres?

Thanks

Wooly
Click to expand...

What load range are the tires? It sounds like they are D rated.
 
wooly said:
The door pillar gives pressure data for 245/75 R16's as 55PSI front and 80 PSI rear.
Click to expand...

The door tag represents the stock tires which are load range E. with a maximum pressure of 80PSI. To get the best wear if not towing, I always run a chalk strip across the tires then go for a ride. When I get the chalk line to fully wear off across the tire I know that tire is sitting flat. Then after towing I go back to this pressure.
 
Ummm seems I have a problem. The story from the beginning!

This is my first truck and it is to be used to pull a fifth wheel. When I bought the truck, the tyres that were on it appeared to have only a few months wear left, just about enough to get through the safety. The dealer offered to install new tyres, at what I thought was a reasonable price. At that time I knew nothing about load ratings etc.

The tyres he installed were Cooper Discover ATR LT265/75R16.

The tyres drove well and were quiet on the road, no complaints there. Today one of the tires looked a little flat. I checked all the pressures and they were all 50psi. Now we are at the stage where I posted my first request for help.

JoeyD's comment about Load Range got me thinking.... what is load range. A quick crash course on the internet to learn about tyres and a quick look at the tyres solve the problem about tyre pressure, but now leaves me with a truck with 4 tyres on that won't do the job. Turns out they installed Load Range C tyres. Looking at the numbers, it seems the tyres will barely support the truck with a moderate load, yet alone hauling a fith wheel at near GVWR.

As well as the dealer selecting the wrong Load Range they also put on 265's vs 245's. Is there any problem in doing that? I did notice the other day with the front wheels turned, that the front of the tyre came very close to the front fender, if my understanding of the tyre numbers is correct then the radius of a 265 is 1.5cm greater than a 245.

Guess all I can do is fo battle it out with the dealer.

Thanks for all the input

Wooly
 
CtChevy427 said:
The door tag represents the stock tires which are load range E. with a maximum pressure of 80PSI. To get the best wear if not towing, I always run a chalk strip across the tires then go for a ride. When I get the chalk line to fully wear off across the tire I know that tire is sitting flat. Then after towing I go back to this pressure.
Click to expand...

Great Idea!
 
HoytBows said:
I had a question about this too. I'm running 285's @ 65psi as it says on the side of the tire. Given that its on the stock rim, i think the tire may be wearing a little more in the center, will dropping the psi to about 55 or 60 help me get a more even wear?
Click to expand...
As said before, read your tread (Bills idea is good) for the right pressure. I run my 285s (on stock PYOs) at around 45 psi. Gives me even tread wear.

wooly said:
Ummm seems I have a problem. The story from the beginning!

This is my first truck and it is to be used to pull a fifth wheel. When I bought the truck, the tyres that were on it appeared to have only a few months wear left, just about enough to get through the safety. The dealer offered to install new tyres, at what I thought was a reasonable price. At that time I knew nothing about load ratings etc.

The tyres he installed were Cooper Discover ATR LT265/75R16.

The tyres drove well and were quiet on the road, no complaints there. Today one of the tires looked a little flat. I checked all the pressures and they were all 50psi. Now we are at the stage where I posted my first request for help.

JoeyD's comment about Load Range got me thinking.... what is load range. A quick crash course on the internet to learn about tyres and a quick look at the tyres solve the problem about tyre pressure, but now leaves me with a truck with 4 tyres on that won't do the job. Turns out they installed Load Range C tyres. Looking at the numbers, it seems the tyres will barely support the truck with a moderate load, yet alone hauling a fith wheel at near GVWR.

As well as the dealer selecting the wrong Load Range they also put on 265's vs 245's. Is there any problem in doing that? I did notice the other day with the front wheels turned, that the front of the tyre came very close to the front fender, if my understanding of the tyre numbers is correct then the radius of a 265 is 1.5cm greater than a 245.

Guess all I can do is fo battle it out with the dealer.

Thanks for all the input

Wooly
Click to expand...
For what you're pulling you need to be running E range. In my opinion, all 4 should be the same pressure. If your truck is 4wd you'll know in 4 hi when the front to rear isn't the same when it starts bucking at about 45 mph.
 
wooly said:
Ummm seems I have a problem. The story from the beginning!

This is my first truck and it is to be used to pull a fifth wheel. When I bought the truck, the tyres that were on it appeared to have only a few months wear left, just about enough to get through the safety. The dealer offered to install new tyres, at what I thought was a reasonable price. At that time I knew nothing about load ratings etc.

The tyres he installed were Cooper Discover ATR LT265/75R16.

The tyres drove well and were quiet on the road, no complaints there. Today one of the tires looked a little flat. I checked all the pressures and they were all 50psi. Now we are at the stage where I posted my first request for help.

JoeyD's comment about Load Range got me thinking.... what is load range. A quick crash course on the internet to learn about tyres and a quick look at the tyres solve the problem about tyre pressure, but now leaves me with a truck with 4 tyres on that won't do the job. Turns out they installed Load Range C tyres. Looking at the numbers, it seems the tyres will barely support the truck with a moderate load, yet alone hauling a fith wheel at near GVWR.

As well as the dealer selecting the wrong Load Range they also put on 265's vs 245's. Is there any problem in doing that? I did notice the other day with the front wheels turned, that the front of the tyre came very close to the front fender, if my understanding of the tyre numbers is correct then the radius of a 265 is 1.5cm greater than a 245.

Guess all I can do is fo battle it out with the dealer.

Thanks for all the input

Wooly
Click to expand...

You need to go back to the dealer and make them replace the tires. Tell them they installed the wrong tires and could have possibly killed you or someone else on the road had you loaded your truck up properly. Do not take no for an answer
 
You need to go back to the dealer and make them replace the tires. Tell them they installed the wrong tires and could have possibly killed you or someone else on the road had you loaded your truck up properly. Do not take no for an answer
Click to expand...

Thats the plan, just putting some numbers down on paper to prove the point.

The Coopers have a max loading of 2470lbs so in theory they can support 4x2470 = 9880 the GVWR is 9200 so i I guess the dealer could claim that the tyres are fit for duty in a legally loaded vehicle, however this assumes that the load is spread evenly over all 4 wheels. Can anyone help out with what the weight distibution ratio might be with an empty vehicle and also a vehicle with 2000lbs sitting over the rear axle. I am assuming that because the rear axle loading can be up to 6084lbs according to the door sticker, that the minimum each rear tyre should be able to support will be 3024lbs. I guess the argument would fall a little thin on the front axle where the max load (according to the sticker) is 4670lbs, which would fall within the capacity of the tires. The argument for changeing those I guess would be that it is not good to mix tyre load ratings on the same vehicle?

Any other points I can use with the dealer would be appreciated.


Thanks again for all the input

Wooly.
 
Check the towing section of your manual Wooly. Lots of numbers there to demonstrate your point with the dealer. In ANY case, they should be ashamed to have put underrated tires on that truck. That's just plain underhanded and unsafe.
 
The truck came from the factory with E-range tires for a reason. The dealer should have replaced with like tire (put pressure on the dealer).
 
Good News

Phoned the dealer yesterday and left a message, first thing this morning dealer phoned with apologies, asked for all the details and told me he'd call right back. Ten minutes later phone goes, dealer had spoken to the tyre shop, and would I bring in the vehicle ASAP for a new set of tyres :thumbsup:

Went to the tyre shop, some seemingly embarrassed faces (I believe it was a genuine mistake rather than a rip-off) and a new set of tyres put straight on the vehicle. No mention of paying the difference in price either :thumbsup:

So all in all, a positive outcome, and a great learning experience for me.

Now all I have to do is let some of that 80psi out of the back wheels when I'm not towing to try and reduce the "bounce"

Again thanks to all for their input

Wooly
 
Glad everything worked out for you. Very nice of the dealer no questions asked, probably a good one to do business with again.
 
Its good that your dealer made things right for you. That could have ended much worse if you had a blow out while towing.
 
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