diabolos88

My question is, on a '88 930, with Bigreds, and a set of kinesis k27's in the following size's:

(2) 9 x 17 et 51 7" backspace
(2) 11 x 17 et 38 7 1/2" backspace


the tire sizes are going to be:

235x40x17 front
315x35x17 rear

would they fit the 930?
What size spacers would I need, if any?

thanks

125shifter

Don't know about the spacing and I would measure the car just to make sure. I measure the spacing of the current wheel and then determine how much clearance is available on each side.

I would suggest 255 front tires since folks I've talked to have said they have understeer problems even using 255's. I've got 235's on my car now and there appears to be plenty of room for 255's. I've got 255's on 9" wheels on the rear of my car and the tire sidewall looks just about perfect.

If you still want 235's, I'd go with 45 series to better match the 315 rears. JMHO.

jimculp

I saw those Kinesis wheels for sale in the wheel section- sweet.

diabolos88

did you mean to say 235's at the end?

125shifter

No, the folks I've talked to went from 255's to 275's in front to reduce understeer.

Even with 255/315 setup, you may need to bias your suspension to reduce understeer. I've got 235/255 now with 22mm front and rear sway bars. I've got the front bar on full soft and the rear at full hard to get reasonable balance.

I still plan to go with 255/315 tires so the steering's not to heavy, but I expect I may have to add rear helper springs and/or increase the rear torsion bar size to get better balance.

kens911

to get the right fit and make sure nothing rubs you have to get the tires mounted and the put them under the car and measure. I had to do that with my carrera and it worked out just perfect and wasnt hard to do. I'll do the same when I get the engine back in my 930.

diabolos88

which 255 would match a 315/35? 255/35, 255/40, 255/45?

nathanUK '81 930 G50

Work it out with this

http://www.net-comber.com/tirecalc.html

Seems the 45 is closer, but neither is exactly the same.

RarlyL8

315/35-17 = 12.4" wide x 25.7" tall
255/45-17 = 10.0w x 26.0t
255/40-17 = 10.0w x 25.0t
275/40-17 = 10.8w x 25.7t

Looks like 315/35 and 275/40 are the same height.

diabolos88

RarlyL8,
do you know if the 275's will rub on a '88 930?

DougM

Not if the rims are fitted correctly with the right offsets.

Dknebes

I am running 8"X18" Kinesis front with 6" inside 2" outside 235X40-18 Michelin sport cups and 11X18 rear 8" inside 3" outside 315X30-18 no rubbing

Seba911

Thats good size... I´m tempting to change to wider tires as well, I´m running 225/18 and 265/18 at the moment, but after rolling one of my wheels beside my friends Countach rear wheel 345/15 my rear wheel looked pathetic

125shifter

I've heard of several people running 275's on the front but they mention rubs at full lock. This would be fine for a track car, but not ideal for a street car.

I'm still planning on 255/40-17 front and 315/35-17 rear on 9.5 and 11.5 wheels. Hopefully I can get it to work on the track without too much understeer. Of course first I have to get my car running.

Dknebes

I was going to go 11.5 rear but decided not to. I would suggest 3.5" outside and 8" inside. It get close to the oil lines on the left side. I am also running coilovers and am lowered quite abit. My front tires are real close to the front spoiler lip where it comes into the wheel well. I had to cut away about 1/4" to keep from rubbing.