Chris,
Drive around the block a few times to get the tires up to temperature,
then put a few stripes of white liquid shoe polish across the tread of
the tire give it a couple minutes to dry. Then drive around the block
again then look at the wear pattern of the shoe polish, if the edges are
worn and not the middle raise the pressure, lower the pressure if the
middle is worn and not the edges when you have an even wear pattern you
have the right pressure.
Doug Hamilton
1960 Triumph TR3A
1963 Fiat Cabriolet
1967 Chev C/10
>Date: Wed, 19 Nov 2003 17:11:05 -0800
>From: "Chris Bohn" <cbohn@sidepipe.com>
>Subject: Cooper Sportmaster metric tires...air pressure...
>
>I've got a set of Cooper Sportmaster Metric tires on my TR4A IRS. These look
>pretty good on the 4A, they have an aspect ratio of 82. Here's my question.
>In looking at the TR4/4A factory manual, I see that Michelin "X" radials
>should run a pressure of 17/24 (front/rear). Dunlop radials are listed at
>24/28. Well, these Coopers have probably the softest sidewall of any tire
>ever. At 24 lbs, you can push your thumb WAY into the sidewall. The contact
>patch looks like a banana slug, with the sidewall bulging out. I am currently
>running 28/32 on the 4A, and the car seems to sit right and tires don't bulge
>out as much; the scraping problems that I wrote to the list a couple weeks
>back are much improved. But, I think I could go a few pounds higher. The
>tires have a max pressure of 44 psi. I'm thinking of going up to 32/36.
>Question to the list: I'm baffled by "recommended tire pressures" since surely
>the recommendation is a combination of what is best for the car and best for
>the tire. My "Tire Guy" has me run my P4000 Pirellis at 40 psi all around on
>my Audi A4, which is quite above what the owners manual states.
>
>My question to the list: Should I run 32/36 on my TR4A with these Coopers?
>Anyone else running these tires?
>
>Thanks,
>
>Chris
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