In a message dated 97-05-23, Bob Allen wrote:
> So you take a tire several sizes wider than stock and put the 'book'
> pressures in it and the ride is squishy. (sp Todd?) Then you pump it up
> a bunch and you discover the handling is much more crisp. I'd say both
> (or either) pressures are right.
Bob, and others:
For the average driver, with no real "high performance" driving experience,
the surest way to determine the correct tire pressure for street use is to
drive the tires for about 10-15,000 miles and check the wear pattern. If they
are worn more in the middle, then the pressure is too high. If they are worn
more at the edges, the pressure is too low. If they are worn evenly, then the
pressure is just right.
That is the surest way, but not the best. A quick and dirty way of doing the
same thing is to take a piece of chalk, and make a heavy mark across both the
front and rear tires. Drive the car for a little bit, as you would normally,
and then check the wear pattern on the chalk marks. Read it just as you would
the wear after 15,000 miles. Just be sure to make the chalk mark of uniform
density across the tires. (this is also a good way to point out misalignment
problems).
FWIW, there is one optimum tire pressure for each setup. Performance drops if
pressure varies from this optimum in either direction. However, performance
drops faster as pressure decreases than it does as pressure increases. A
little error in the high direction is better than an error in the lower
direction.
For high performance driving, there is a whole 'nother set of concerns, as
you pointed out!
Dan Masters,
Alcoa, TN
'71 TR6---------3000mile/year driver, fully restored
'71 TR6---------undergoing full restoration and Ford 5.0 V8 insertion - see:
www.sky.net/~boballen/mg/Masters/
'74 MGBGT---3000mile/year driver, original condition
'68 MGBGT---organ donor for the '74
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