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From: dove@fortune.UUCP (Michael Dove)
Newsgroups: net.auto
Subject: Re: tire inflation pressures
Message-ID: <5358@fortune.UUCP>
Date: Thu, 11-Jul-85 16:41:55 EDT
Article-I.D.: fortune.5358
Posted: Thu Jul 11 16:41:55 1985
Date-Received: Sat, 13-Jul-85 09:12:25 EDT
References: <572@hlwpc.UUCP> <1765@amdahl.UUCP>
Distribution: net
Organization: Fortune Systems, Redwood City, CA
Lines: 48

> Carl,
> 
> I have a 77 Trans Am and have always kept the tires at the tire
> manufactures maximum (checked cold).  Mileage is better, and the tires
> are wearing fine (over 55K so far).
> 
> Car manufacturers seem to be more concerned with getting a softer ride
> than with tire wear and possibly reduced cornering.  Though I thought
> they were supposed to be concerned with mileage....

For most passenger car tires, following the tire manufacturers maximum
pressure is fine.  But you run into problems.  Usually associated
with those maximum pressures is maximum load, which also must be
taken into account.

Most off road tires, you can not follow this rule.  Since the weights
of off road cars differ so much with respect to the tires people are
putting on them.  There are Toy Mini's which could almost blow over
in the wind, with 42 inch tires on them, and big heavy Bronco's with
30 inch tires.

I have 31.5-10.50x15 BF Goodrich Radial All-Terrain, TA's
on my Landcruiser, and I am 20 lbs below manufacturers maximum.
BF Goodrich has a maximum rating on these tire of 50-55 psi
(I do not have the exact number), and over a ton (around 2200 as I
recall), per tire.  That means 50-55 psi is fine if you have a
4 ton car, but who has one of those.  I run mine at 32 average psi
and have very good wear all across the tire.

Since off road tires cost considerably more, people who purchase
off road tires usally will do all they can do to get the most
mileage out of their tires.  One of the things I do is have
my car weighed at all 4 corners, then base the pressure to that.
All cars have different weights on each tire.  Left-right weight
changes are usually not much ( basically you are the delta ), but
front to rear can sometime be dramatic.  Then if you make the pressure
slightly higher on the heavier end, your tires will wear better all
around.  Plus handling, braking, traction are improved.


-- 
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 *                                        *|
|*  Michael Dove                          *|
|*  Forutne Systems Corporation           *|
|*     {ihnp4, ucbvax!dual}!fortune!dove  *|
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