Steve Rea

While I will be eventually putting a full coilover suspension on my track-only car, now it's got the stock, '87 turbo suspension on it. Will the following wheel/tire work for a track, shake-down weekend?

wheels:
18x8 & 18x10 hollow spoke turbo twists (oem)
55 and 60 offsets I believe (maybe 52&60)

245x40x18 front
275x35x18 rear

Toyo RA-1's

Thanks,

Steve

Matt H

Try a 225/40R18 up front and a 285/35R18 in the rear.
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Dan Hovang

It depends on how much camber you want to run. If you run 2.5" or 2.25" springs and adjustable top mounts, even 255 will fit and still allow for good camber. It is possible that you have to sacrifice scrubb radius for camber though.

Oddjob

Steve,

As you know the 18" Toyo RA1s only come in limited sizes. 225/40, 245/40 will be your only choices on the front and the 245/40, 275/35 on the rear (the 300 sizes wont work). I think youre correct picking the 245 and 275s. They should work on your car with the 52 and 65mm offsets (OEM 10x18" Twist whls are either 47 or 65, 47 wont work).

I have run 245/35 front and 285/30 rears (hoosiers) on 8 and 10 speedlines with 52 and 65mm offsets on my 87 with no problem. But it has stiff suspension, rolled fender lips, -2.5 to -3.0 camber, and used 1/4" spacers in the back (only had about a 1/4" gap between the tire and trailing arm w/o the spacer).

Keep an eye/ear open for rubbing. You will have quite a bit of body roll with stock suspension. Rubbing is possible and if it does happen, it will likely be the unrolled fender lips cutting/rubbing on the tire sidewall on the rear, usually right around the shoulder (bad spot for it to cut, but the toyos are pretty tough compared to hoosiers). But watch the fronts too.

Z-man

I dunno .... I run 245/45-16 on the fronts when I track my 944S2. 245-40-18 is, IMHO too tall a wheel/tire combo.

I don't have any rubbing issues with my setup, but I suspect that you'll get some rubbing no matter how heavy a spring setup you use.

Just my $0.42,
-Z-man.

PS: I hope you don't have the stock A-arms on your car! 18" wheels are heavy, and if you've lowered your car, that combo can cause excessive wear on your ball joint.

Dan Hovang

I had rubbing on banked corners with 225/50-17 front and -2.5 degrees of camber on OEM suspension.

DDP

Will 235 fit up front on 17 turbo twists with mild camber and stock suspension?

Matt H

It can be mounted on the wheel BUT it is really too big and it not the best setup for the car.
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DDP

So you suggest a 225 Matt?

Matt H

What are you doing with the car? I have 225s mounted on my 7s if you want to swing by and check them out (hell you can take them for a spin if you feel like putting them on yours for a little while.
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DDP

Im driving my car. I want to get into autoX and pca next summer. I will have 255 on back but I thought I wanted the largest I could fit on front to try and dial out the understeer. I know this isnt the best solution to my understeering problem but its the cheapest way for me right now, and Im not even sure of how much it could help. I have 215s in front right now. I didnt have much understeer with those because my rear tires were bald. What kind of tires do you have on those rims, Matt?

Z-man

It's not just the width of the tire that matters, but it's aspect ratio as well. For example, a 245-45/16 yields a tire/wheel diameter of 16inches (wheel) + 220mm (tire sidewall), whereas a 225-60/16 yields a tire/wheel diameter of 16inches (wheel) + 270mm (tire sidewall).

If you are setting up your car for autocross, then go with 16's, unless you've upgraded the brakes and the 16's won't fit around them. 16's tend to be lighter, and if you're getting autox only rubber, then you can go with a lower profile. (something like a 225/35-16 on 7Jx16's in the front) That way, you have a smaller diameter and a smaller circumference, which essentially 'creates' lower gearing for your car. You'll have less top end (who cares) and a bit more umph off the line, which you want.

Since 17's were never offered as an option on ANY 944's, then you do realize going to 17's will bump you out of stock classes, right?

Oh, a little bit about understeer: what kinda suspension do you have on the car? If stock, the I suggest getting a thicker REAR sway bar (like a 968 M030 19mm 3-way adjustable or a Welt 22mm adjustable) and keep the front sway bar stock. Firming things up in the back will help dial out some of the understeer. Another thing you can do is run the same size tire front and back - that works very well - I run 245-45/16's at all four corners on the track (DE) and when I can stay in stock classes in autox as well. Really, really helps. If you have a strut tower brace over your engine, then I also suggest that you take it off and use it as a towel rack! (I'm not a big fan of STB's - can you guess?!?)

Just my $0.42,
-Z-man.

Dan Hovang

I think having good camber will give better grip rather than increasing tyre width by 10 mm (which is less than 5%). But to do both is ofcourse the best

The stock suspension understeers alot even if you have same tyres all around. The only way to get rid of that is to change the suspension, or apply more throttle.

Danno

How about a 245/35-18 front and a 285/30-18 rear combo? Those would have diameters closer to stock.

DDP

Thanks for all the info.

I am well out of the stock class with my engine anyways so that doesnt matter. I want to try the 8s all around but I cant get my hands on a set. My turbo twists are very heavy, at least compared to my BBSs. Yes my suspension sucks and Im not going into it. You will laugh at why I have so much understeer. So...thanks for the info.