Question-Thanks again and I apologize for the mistype. The Front tires are recommended at 35 and the rear are 40 (I mixed it up). I am familiar with the 9% difference, however, the new tires have a load rating of 2270lbs. each at 35 lbs. so shouldn't I be OK? My truck surely doesn't weigh more than 8400 lbs.
Lou
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Followup To
Question -
-Thanks. My panel indicates the preferred tire to be a LT 265-75-16. Front inflation recommended is 40/280. Rear is 35/240. My new tires are Liberator All Terrain P255-70-16's. My mechanic tells me that it doesn't matter how much the inflation is on different tires, all that matters is the load range. is that true?
Lou
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Followup To
Question -
Hi,
I own a 1993 Chevy silverado Z71 4x4 extended cab...350, v-8, 5.7. I needed new tires, but with 250,000 miles on my truck, i did not want to buy real expensive tires. The tires i ran were LT266-75-16's. I went to walmart and they convinced me that i could run P255-70-16 Liberators on my truck. So, I purchased them. My question is this....is this tire's load range and rating OK to run on my truck and will the difference in size and make make a difference in safety. My previous michelin tires had a max. inflation of 50 lbs. and with a load range of 2270 (I believe). The Liberators have a load range of 2270 also, however, they are a passenger tire. Please advise me on this. Thank you.
Answer -
Lou,
On every vehicle sold in the US is a placard that lists the original tire size and the proper inflation pressure for that size. On Chevy trucks I think it's somewhere in the driver's door area.
Unfortunately, I can't look this up, because there are so many versions of Chevy trucks.
Post back when you've got that info.
BTW, it's a good thing you noticed the letters in front of the tire size - They are important.
Answer -
Lou,
There are parts of the info you provided that don't make sense:
1) It is unheard of for the front tire pressure to be specified higher than the rear tire pressure.
2) LT265/75R16's normally are spec'd with at least 45 psi.
So would you please check this info again.
BTW, your mechanic is wrong about the load range. Perhaps he means load rating, like the maximum load or the Load Index. But even then - if your vehicle came with LT metric tires (starts with the Letters "LT"), then in order to get the same load capacity in P metric tires (starts with "P"), then the P metric tire has to be derated by 10%.
PLUS
The inflation pressures have to be specified so that the load capacities wind up being the same - placard vs current - based on what you've written the P255/70R16 would not have enough load capacity on the front, even if the maximum inflation pressure were used..
AnswerLou,
Engineering a vehicle is not a simple task. And experience is a great teacher. So why not use all the experience GM has in designing trucks - and the tires that go on trucks? I personally have over 30 years experience with tires and when I disagree with GM on something, I do it very carefully.
So when it comes to load capacity, I assume GM follows good engineering practice by specifying tires with some level of reserve (unused) capacity (I know that that Ford didn't do this, and look what happened.) This is also a safety issue as the less capability of a product you use, the less likely you are to have a failure due to unforseen circumstances.
Besides it's not what the vehicle weighs that is important, it's what each individual tire is required to carry. Any overloaded tire is likely to fail.
And a P255/70R16 for a light truck application has a maximum load capacity of 2064 lbs at 35 psi. This would be suitable for some P/U's, but based on what came originally - not yours.
Hope this helps.
