121cup

i have a 1995 993 factory cup car. Original factory specs call for 245/650 front and 285/650 rear. no such thing anymore.

I can cram a 250/640 dunlop in the front but cant fit the 280/660 in the rear, so dunlops out. I can put a michelin 24/64 in front but am pretty sure the 27/68 will not fit the rear well - all other michelin options would be a front tire application in the rear . . .not ideal and i have experienced side wall failure when i tried a similar strategy with the dunlops.

there are rumors that yokes and hoosier make the fronts but the rears are again not exactly the correct size AND I really like the michelins from past experience - what are options these days??


francesco

fstockcarrera

Are sure a 280/660 won't fit. Yokohama makes a 280/650. That should work, but the dunlops in my experience are a touch faster.

Red9

When comparing different tyre brands-- you need to measure across the surface area-- not rely on stated width. There is quite a variation that makes a big difference when fitting.

121cup

Hey Bob, the dunlop 280/660s dont fit and get chewed on the sidewall by the fender. i liked them too but now not an option.

Michelin recommends the 27/68 but that seems big too - any experience with these?
Alternatively i could use the 27/65s but they are for a front application and cant take the load of a 911

fstockcarrera

I believe John Geotz at Dan Jacobs shop runs dunlops on his 993 cup. The car is not at Dans Shop. I don't have John's #. The other guys run yoko's. How much camber are you running???

Bob

coryf

We also have run the 660 on the rear of a 993 cup. Are your wheels the same offset as the original 993 cup?

BrandonH

I'm using 285/645 and 235/645 Yokos and Hoosiers

121cup

so we had to crank in camber 4.0 - although the factory book calls for even more 4.5-5. also we had to come up from the factory book ride height about a centimeter and now the michelins and dunlonps fit fine.
will run the car at NJMP for the kojote event and see how it feels.
Thanks for all the input!!

BrandonH

Yes I'm running outrageous camber close to 5. Peter Dawes says they spec'd them this way in Europe to encourage the car to corner on two wheels around medium speed corners to get the car up and over high FIA curbing. All I can say is it grips like the Hand Of God in the Octopus corner at Thunderbolt, but is somewhat squirrelly under heavy breaking at the end of the straight.
Whatever the case may be, it is hard to see the tires fitting without it.

jdistefa

I run the Michelin 27/68 in the rear with the fenders rolled.

If you run this size in the rear, you'll need to change the ABS gear wheels in the front to keep the computer happy.

PM me if you have questions. Agree you shouldn't run the 27/65 in the rear.

121cup

so complete success! i was happy with the set up at NJMP. car stuck like glue with the michelins but it definately was front hunting under heavy breaking at turn one with all the additional camber.
i had not considered the ABS rotation sensor - i will look into it immediately.

Next event is the SVRA "zippo" historic at the Glen in September, we will see how she runs.