Tom R.

The car came with a 205/225 setup. I asked about a 205/245 setup from a 930.

Extra understeer was the answer. That started a heated discussion.

Go to Tire Rack and punch in a wheel and tire package using 17" rims.

Suggested size 205/255! WTF?

For 18" wheels it is 225/255.

And you thought/know a 205/245 setup is going to add understeer. And Tire Rack is the more respected places to buy from.

MPD47

205/245's understeered, though I COULD kick the rear out in the corners. My new setup is 245/265s so I'll see how that does.

dave120

I went from 205/225 with my 16" D90s to 225/255, doesn't understeer on my 17s. 205/255 will understeer a good amount unless you stiffen up the rear suspension. It works on 911s, but not favorable for 944s due to the weight being a lot more balanced.

I think with these cars it's generally better to keep the tire sizes as close to each other as possible since the weight balance is so close. I'm not sure if that's true or if I'm recallig incorrectly though.

Rich Sandor

Stock 16x7x8" 205/225. w/ street tyres: not enough traction in the rear, and lots of understeer.

MM cup1 replica's, 17x7.5x9" 215/255. street tyres: way more traction in rear (until the rubber wore out..), more grip overall, but still a bit understeery at high speeds, and a bit clumsy feeling at lower speeds.

I think a happy setup for me would be 17" wheels with 8" at 225 or 235 in front, and 9 or 10" rears with 255 or 265 rear rubbers. Also w/ the 17" wheels (or even without) the new 968 castor block helps a lot. but then my car has about 50hp more than stock, and no lsd, so having bigger/stickier tyres helps keep from just one wheel braking loose.

pete944

You have 16" wheels, right? What are the widths?
For 16's go with 225 or 245 all around or 225/245.
I have 205/50 and 255/40 on my 17" wheels and I want to go to at least a 225 or 235 in front when I need new tires. They came off a 993 and 993's work well with the staggered tire size but I feel the 944 is a little better with closer sized tires.
It's the same with my 18's, 225/40 in front and 285/30 in back. Still too much understeer.

Serge944

225/45 seems like the way to go.

Rich Sandor

You should match your rim width to tyre width, though. If you put excessively wide tyres on a narrower rim, you can get very noticeable sidewall flex. On the otherhand, it would be an utter waste of money to put for example, 205's on a 9" rim.

As a rule of thumb:
6" rim = 195
7" rim = 205
7.5" rim = 215
8" rim = 225
8.5" rim = 235
9" rim = 245/255

Does anyone know if anyone makes tyres that are inbetween widths? ie: 220, 230 or 240.?

AndyK

I always figure the engineers that designed the cars knew best...is that wrong?

pete944

Tire technology has come a long way since 1989. Many of these sizes didn't exist when the cars were designed.

Tom R.

a 205/245 setup will give extra understeer. a 205/255 setup will give even more understeer.

Yet tire rack says go from 205/225 to 205/255!

sweanders

They also needed to consider that it is safer to crash in an understeering car since it will hit whatever is in the way front first.

bader$

I run 205' and 225's on 16X6-8's and mine does fine if you keep the air pressure right. Of course I am not racing or auto crossing.

adrial

Tire rack doesnt know everything. Most likely they suggest that because those are the wheels that they have. A lot of the 17" wheels available for our car are 17x7 and 17x9.... ie 205 and 255.

Tom R.

adrial
saw the new sig. congrats on getting it moving.

Z-man

Tom R: 225/245 is a good starting point. It is a +1 from the stock 205/225 setup. Traction is increased with the 225/245 sizes, but the understeering issues still prevail. Your D-90's are probably 7" front, 8" rear, so that's about all you can do with them.

HOWEVER, if you really want to dial out the understeer (for applications like DE or autox), then you need to get an extra set of 8's for the front. 245/45-16 at all four corners yields a very balanced car, better turn in, and that setup is NOT too much for the suspension to handle. There are also no rubbing issues with 245's, even with R's and a sloppy, worn stock suspension!

This is my second season of running R compounds with 245's at all corners on the track. Totally changes the car's attitude in the corners!

Just my $0.42,
-Z.

PS: Adrial: the car will be there for P-Rama, right? Wonder if I can borrow the car for the autox portion of Porschrama. (At least for one run a day!) I know: I'll run right before you to warm up your tires!