simplex

After years of running autox on street tires, I'm curious to try out the Hoosiers.

My car is a 991.1 C2 base (not S) on passive dampers (not PASM) on 20" stock rims.
This brings up a couple of questions:

1) Can I run Hoosiers with my suspension as-is or do I need to mod it to add negative camber?
2) I have the option of 20" R7's on my existing rims, or getting 19" rims with A7's. (There's talk of 20" A7's but at this point it's unknown when and in what sizes). Which of these options is best?

All constructive opinions and advice are appreciated.

PedalFaster

1) You can run Hoosiers on anything -- back in the day people ran them on Minis, Civics, and the like. Having said that, R-compound tires are more fragile than even performance street tires. In the bad old days, some FWD cars could only get a dozen runs out of their front tires before cording them. Your car shouldn't be nearly that bad, but regardless, if you run Hoosiers, expect noticeably worse tire life. Conversely, if you modify your car to add negative camber, expect significantly worse finishes since that'll put you in A Street Prepared if you run with the SCCA.

2) A7s are significantly faster than R7s. If speed is your top priority, run A7s. If tire life is a more important consideration, you're best off just sticking with street tires.

simplex

This is very helpful, thank you!

I will then likely go for A7s on my stock suspension.

jwr9152

Definitely go A7 over R7. I tried a set of R7's and struggled to get heat into them. Afternoon runs in the summer weren't bad, but cool morning were pointless. Having a co driver would help, but you will still be throwing away some runs trying to get heat into them. Hoosiers will work better with negative camber in them. I was running around -3 degrees. On the plus side they lasted a season.

You'll also need a trailer to get your car to and from events. Would not be fun to get caught out in the rain on them. I got worn out switching tires out at events, so I switched back to RE71R's. I was driving an Audi S5 at the time, and could fit a full set of wheels/tires in the back. Getting the itch to try a set on the 991, but I would definitely need a trailer first.

Earlydays

I ran Hoosier A6's on my 964 when I was in A Stock (early 2000's) with about -1.5 degrees all around. I loved the way the car handled. I recall I had to run rather high pressures, more than I run on RE71R's today.

simplex

Thanks! Wow, –3 deg would require some major changes to my suspension.
Not sure I'm ready for such an investment...

On the second point, I may just ask my wife to drive our Macan as a support vehicle with the wheel/tire set.

simplex

Thanks. From your memory, how's the grip comparatively speaking between the A6 and RE-71R?

Earlydays

I would say that the RE-71R is easily a match for another R-tire that was popular in those days, the Kumho Victoracer, but not yet up to an A6/7.

simplex

Makes sense, thank you.

PedalFaster

To be clear, both street tires and R-compound tires work better with more camber than a 991 can get stock.

You can make a rough estimate from the PAX factors for SSR and AS. SSR's rules and cars are essentially identical to those for AS except for the R-compounds like the A7 are allowed. According to PAX, on a course that takes an AS car 60 seconds to navigate, an SSR car will take 58.3 seconds -- nearly two seconds faster!

simplex

Yes, I understand that running autox on stock geometry is suboptimal.

That's a good estimation method. And the time difference is certainly impressive!