upcruiser

Here's my situation. I've got an '83 944 that I'm looking to use a bit more heavily for autocross and some track events this coming season. I'm going as far as to say that if funds allow, it will become a dedicated track car, though I would like it to remain street legal.

I have two sets of wheels for the car, both of which are at the point of needing new tires. The original set for the car which are the 15x7 cookie cutters and a set of Mille Miglia Cup II replicas (993 look) which have the huge backspacing in them to allow for correct offset on an early 944. The Cup II's are 17x7.5 up front and 17x9 in the rear. These tires allow for a pretty large contact patch but seem to have some drawbacks. I haven't weighed them but I know they are pretty heavy, mostly due to the design of the wheel and backspacing. Also I realize that rotational mass might be higher then on the 15's which may affect acceleration.

My question really boils down to this. Would it be more beneficial to me to use the cookie cutters, with a smaller diameter tire, maybe a dedicated slick, or go with something similar for the Cup II's? One way or the other, I could use the second set for some street tires. Is the effects of a smaller diameter tire on the 15's enough to counteract the amount of lost contact patch?

I realize the basic handling effects of the wider rear tires and as I do some set up work on the car, would change settings to counteract them depending on which route I go.

I know alot of guys here track their early na's, so I'm hoping to get some good feedback.

ekeeton

For autocross go with the smaller diameter wheels for better acceleration/deceleration.

Reduce unsprung weight is a basic principle of race car engineering. There has to be some other strong reason to override that principle.

All theory aside, go to the track and see what the fastest cars are doing, then do what they do, if you can.

upcruiser

That's what I figured regarding the smaller diameter wheels/tires but wanted to confirm that perhaps. Problem is, where I live, I don't see any other 944's running events locally, and the ones that I'm considering for next summer, I'm hoping to go to with some work done already.

The other question I meant to include in the original post was, for those who are running 15x7's, what size tires are you running on them?

MAD MAC

If you run big brakes you may run into a clearance issue with the 15's.

Techno Duck

The popular size for 944's running 15x7 in my area is 225/50/15. You might be able to find 225/45/15 but you probably will only find this size in an r-comp tire, like V710's, V700's...etc.

Use the replica's for street use and keep the cookies for auto-x, they are a really lightweight wheel and tires will be cheaper. My friend has a set of turbo twist replicas and they are incredibly heavy.

tifosiman

Stick with the 15's and get some Hoosiers. You'd get clobbered at an autocross with those repro 17's.

upcruiser

Still planning on running the stock brakes, just upgrading pads and fluids.

upcruiser

Great, thanks for the size feedback especially. Are the cookie cutters similar weight wise to the same size Fuchs?

upcruiser

My last autocross I managed a 5th fastest time of the day out of 36 cars despite my stock suspension (with some REALLY worn out shocks) and the 17's. I just couldn't help to think how much better it would have been to be on the 15's.

You guys are making my mind up rather quickly!

upcruiser

Oh, and another question, the tire I was looking at was the Hoosier A6. From what I read it is designed for autocross primarily. Will I have heat issues with it on road course track days? I'm curious if it would be better to go with a heat cycled R6 instead. I did a quick search and found them both available in 225/45's so either the A6 or R6 sound like contenders.

Techno Duck

Take my advice with a grain of salt here because i am pretty new to a R-Comp type tire. The A6 will probably not be very good on a road course as they are designed to offer maximum grip with minimal heat, meaning you will probably heatcycle these out on a track very quickly. The R6 compound can take the heat punishment but will take longer to get heat in them. Im not sure how long it would take to get a desirable level of heat into the R6 at an auto-x type event, or if you would ever get enough heat into them to make them sticky.

Have you considered the Toyo RA-1? Ive read great things about these tires and many people use them for dual purpose track and auto-x use. I also know a few people that run them on the street all the time. They will never be as competitive as say a Kumho v710, but still offer good grip over even the best summer tire ive read. These also last stupid long i hear.

tifosiman

Hoosier A6's will kill the RA-1's. The RA-1's are slow to come up to heat and do not stick that well at an autocross until the 3rd run (if you have a small turn-out of competitors, if it is a large turn-out and a long time between runs you are screwed). The RA-1's are better than a street tire, but not the best for autox.

knfeparty

I've got a similar situation with my 89 944. It has 15" phone dials and I had planned on getting another set of wheels for autox (and maybe a couple of track events). I found some 16" (which are wider in the back) phone dials. Is the wider contact patch going to help or is there going to be too much of a difference in weight? And could someone fill me in on exactly what wheel is the really nice lightweight one...Fuchs, right? But what do they look like? Are they all 15"?

upcruiser

Your 16" phone dials are 15x7 and 15x8 I believe. I know that with my car, switching to the wider rears gave me noticeably more understeer from turn in to apex, but on exit, if I did things right, it also allowed me to lay down alot of traction on exit under power. Despite more of a tendancy to understeer, its still pretty easy to hang the tail out i I want.

Fuchs are the classic Porsche wheel used since the late '60's through '80's on various Porsches. From what I recall, they are supposedly lighter then comparable wheels (cookie cutter/phone dial) of same size. Not positive though, thus me asking in the beginning of the thread.

pjburges

I am running 15X7 cookie cutters on my 924S which I assume has all the same suspension offsets and geometry etc as the pre 85.5 944's. Im thinking about converting to turbo brakes which would mean turbo knuckles and 16" rims. Is there any particular offset of 16" rim that you should look for to maintain the pre 85.5 steering geometry?