tire inflation chart, max load vrs. normal driving

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jeff - 12 Dec 2005 22:42 GMT

I have Michelin 30x9.5 RI5 LT 104R LTX M/S tires. These are the tires I
replaced the Firestones with. The Michelin website says Max. load is
1985 @50 psi. They don't give a tire inflation number, other than
that. Is that "maximum load" the weight of my car? I don't normally
haul a load, except going camping.
What is the suggested tire inflation psi for normal commuting (one or
two passengers, full tank of gas, not carring a load, not off-road)?
Just that same number, the 50 psi?
Also, I've heard that the normal life of a tire is 5 years, even if the
tread is good. I put about 10,000 miles a year on my car.
Thank you,
Jeff Myers

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Hairy - 13 Dec 2005 03:50 GMT

> I have Michelin 30x9.5 RI5 LT 104R LTX M/S tires. These are the tires I
> replaced the Firestones with. The Michelin website says Max. load is
[quoted text clipped - 8 lines]
> Thank you,
> Jeff Myers

You don't say what "car" you are driving, but I'd probably start at about 32
psi or go by the car mfg recommendations.

Dave

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Ed White - 13 Dec 2005 13:36 GMT

I assume these tires are on an Explorer. Since you have changed from P
series Tires to LT (Light Truck TIres), and changed the size as well,
the original Ford recommendations for the vehicle no longer apply. For
a given load ratng, LT tires require a higher pressure than P series
tires. This is becasue LT tires have stiffer sidewalls that generate
more heat when flexed. You tire dealer should have a copy of the
Michelin Load Inflation Tables, or at least the Tire Guide which will
also have the industry standard load inflation tables for this tire
size. Or you can look on line at -
http://www.yokohamatire.com/pdf/tsb-070302.pdf . This reference
suggests that you increase the Ford recommended pressure by 15 psi when
changing from a P series tire to an LT series tire. I think this is
excssive. But you at least need to run 35 psi in your new tires.

Ed

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