FWIW, a whole lot of years ago, after my first few autocross passes with
Bridgestone RE71s on 7" rims, I noticed the suspension had flexed sufficiently
to allow the rims to chafe the front brake caliper balance pipes. Just because
there's no interference at rest, don't make the mistake of assuming something
isn't happening under heavy load. If you're exercising the car, a periodic
visual inspection is mandatory, even if you aren't going to the extent of NDT.
And as Mike said, the fatigue effects of added loads do a job on the A-arm
bushings and ball joints, too.
- Bob Mann. '68 2000 Solex -- new balance pipes
datsunmike wrote:
> Yep, those wide tires can over-stress the front end as the tires provide
> more grip than the suspension was ever designed for. Today's modern tires
> are grippier than F1 tires or almost any other tire made in the 60s.
>
> While nothing may break if you drive sanely, if you start doing all kinds of
> tricks you may soon see what it can do. The frame is known to crack at the
> upper a-arm attaching points and those wide tires may speed up the process.
> Several listers have broken front end parts using wider grippy tires.
>
> Your suspension should be checked thoroughly and many racers have their
> a-arms and other parts magnafluxed and shot blasted to relieve metal stress
> and fatigue.
>
> Mike
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