wheels, tires, and flares Options

[ottox914]

While building the next generation turbo motor for the 914, thoughts turn to putting the power down. I'm currently autocrossing with 205-50-15's on 7" wide Keizer rims, with a slight pull of the rear fender, the return lip cut off, and some spacers to keep things from rubbing on the inside. Puts about 8.3" on the ground for the 710's I'm running currently. I'm expecting around 200 whp, with a class min wt for the car of 2150 or so. I don't see a need to convert to 5 lug, as I have some nice panasports for street driving that I like, and the bigger brakes wouldn't buy me that much in a 60 second autocross. On a road course, yup, bigger brakes better, for autocross, lets keep it light. Car runs in what used to be SM2, is now SSM. Here's the kicker- even with 4 season old 205's, in 150+ car grids, with several national jacket winners and a dozen or so trophy winners, I can put the car in the top 20, top 10 if I have a great day. So how much more tire do I really need to have fun locally, which is what the intent of the car is. I know it will never be the perfect weapon for a season of divisional/national events in SSM.

Here are some options I'm considering:

- run 225-50-15's on the same 7" rims, do a little metal pounding/pulling to keep a basically stock looking fender profile. This would add about an inch of rubber on the road from the 205's, and be the cheepest solution, other than just staying with the 205's

- run 245-50-16's, which would require new rims in a 16 x 8 size, 4x130 bolt pattern. Diamond racing makes a 20# rim for $150 that would work, (but is a little porky) has a 4 1/2 back space, should fit under a standard GT flare, but this means more $$$, rims, FG flares, install, in addition to paint. It only adds about 1.5" from the 205 size contact patch, only 1/2" from the 225's. I don't expect I could get all that much for my Keizers, and new ones would be what, 1200 to 1500 or so? Thats alot of green.

- run the hoosier 275-35-15's, which like a 9.5" rim. I could get new hoops for the keizers, and keep the inside hoop and hub, which would keep the correct back space and bolt pattern for the car, would still need flares and paint. This tire puts 10.8" on the ground, approx. 2.5" up from the current 205's. Haven't checked lately, but don't think I can tub the car in SSM, although in XP that would be allowed.

Anyone running the 275-35-15 on a 914, or anything similar in a tire/rim/flare combo? Can it be done w/out making the car stupid wide, which of course would not be the best for slithering thru a slalom? Up north here in WI, the guys running slicks have problems for 1/2 the season- it just is so hard to get even the softest of them up to temp unless we have hot sun and 90 degrees out, so I would plan to stick with the DOT "R" rubber.

Thoughts?

[J P Stein]

Again I'm assumimg you're gonna have the power you want. There is a reason for the fat rear tiar recommendation....the traction circle. All your front tires have to do is turn and can use all their grip to do so....more on this in a bit.
Your rears have to turn & and push the car forward, thus less grip is available to turn. The more motor you have the more critical this becomes......big sideways looks cool but it's not the quick way around. The grip of the fat tires allow you to get on the gas sooner.

Up front, you need to watch out for excessive scrub radius. I wasted a whole season trying to get rid of a tight turn push using 10 inch wheels. The steering effort was also very high. All my efforts to cure this made the car oversteer like a bitch on the fast stuff.
I finally figured out the scrub radius deal. Went to an 8 inch wheel (which reduced the scrub by 1 inch) and we were in business. The front tires are only slightly smaller. Spacers up front will also increase the scrub. As you said, getting heat in the fronts is a problem on cold days. Getting heat in the rears is less so...if you have the grunt.....push rears its head again.