QuestionQUESTION: I have an 04 Silverado and pull a 22' trailer. I am well within my spec'd
weights for the truck in every aspect.
I switched to LT Michelins M/S Load range E from the OE p rated Goodyears.
I have heard that the stock wheels will not handle the max psi I can put into
the E rated tires. So I air them up to 60 psi while towing and around 40 for
daily driving. Some say that I need to take my tires to the max of 80 or I will
risk overheating and premature wear. I think this is a bit extreme.
I have also seen load curve charts somewhere but don't know where that was
can you direct me. I would like to do the math and figure what my psi should
be on with my load for these tires
ANSWER: Jeff,
Unfortunately these load tables are not allowed to be published. The book they are in is the only source of revenue for the folks that publish them - the Tire and Rim Association - although you will sometimes see portions on the 'net.
Why don't we do this.
Tell me what the vehicle placard says: tire size and pressure for that size. Then tell me the tire size you have on there now, and I'll do the math for you.
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QUESTION: Thanks for the reply.
The plate calls for
P 245 75R 16
Front psi 30
Rear psi 35
replacement tire
Michelin LTX M/S Load range E
LT 245 75 R 16
Max load 3042 @80 psi
ANSWER: Jeff,
A P245/75R16 has a load carrying capacity of 1914 # at 30 psi and 2065 at 35 psi.
An LT245/7R16 gets that same load carrying capacity at 42 and 46 psi.
Now just to prove those are the correct pressures, why don't you do a pressure buildup test.
The next time you are towing, measure the pressures before you start your trip. Then measure the pressure as you going along. I would suggest that you should measure every 30 minutes until the pressure stabilizes.
What you are looking for is no more than a 5 psi buildup - lower would be better. If you get more than 5 psi buildup, something in the raw data is wrong. If so, add 5 psi until you get no more than 5 psi buildup.
Hope this helps.
---------- FOLLOW-UP ----------
QUESTION: I understand the Load of the LT at 42 and 46psi..thanks I can run this when not towing.
but how can I figure 50 or 55 or 60 psi.. 60 is where I run at when towing. I am just trying to get the best sidewall I can with the load I am running?
also what about the psi max on my stock rim. How high can I go before I exceed max rim psi. I am sure I am not suppose to run 80psi?
And will I run into any problems running at these psi.
to much heat, sidewall rollover, bad tire wear.
thanks for your patients. I well pass on this info and help alot of people doing the same thing I am doing..
AnswerJeff,
If you are operating the vehicle within the towing limits as established by the vehicle manufacturer, then 42 and 46 psi ought to be adequate.
If you don't believe that, then run the pressure buildup test. That will prove whether more pressure is needed.
BTW, that pressure is based on the original tire size as indicated on the placard - and the tire size you currently have on the vehicle. This might be different for other vehicles and depends on what the vehicle placard says and what tire size is being used.
