iLLM3

Definitely not!

And there will be tons of people to argue this little article as well.. I for one cannot go less then 315's in the rear, and there is no way im getting 315's up front, and even if I did the steering input would probably be terrible with so much rubber!

smlporsche

It's funny. The three things they did are commonly done to cars racing in the 944 SuperCup series...
Although I have yet to measure it but going to 245's on all corners and getting the upgraded MO30 sways my car can easily corner over 1 G. With RA-1's I'm consistantly getting 1.2+ G's accordint to my Traqmate.
I always thought that the primary reason 911's had larger rear tires was to reduce the chance of oversteer with all that weight behind the rear axle (and of course get better traction comming off a corner).
I think the article was focused on mid to front weight biased cars. Those with a mid or rear engine platform can benefit from a larger rear tire. Of course it doesn't hurt to increase the width of your front tire a little...

M758

Um,
the RSR is a rear engine car, The 430 is rear/mid engine car. Both carry more weight on the rear tires than the fronts.

A more common front engine/rear drive car most often does benefit from similar sizes from and rear. Even so it is just one factor in performance.

Bryan Watts

I'm not aware of any such difference in staggering between US and European BMW's.

Bryan Watts

If you're running a high powered rear engine car, going to a square wheel/tire setup probably isn't a great idea.

iLLM3

And where did I argue against that? What I was trying to point out is the topic is almost meant for all cars, which in the test isn't the case , and does not apply to every car/platform especially the rear engine cars

ZAPmobile

I guess all the race engineers at Porsche, Ferrari, Mclaren Honda, BMW, Mercedes, Renault, etc are not very smart. They'll have to go back to school and read this article.

hacker-pschorr

Ok, for the record I originally posted this in the 928 forum as an FYI to 928 owners and their street cars.

I also said this is one of the reasons I'm going with equal tires all around. I like the idea of being able to rotate my race rubber. I'm not 100% ***** to the wall like some of you club racers (not saying this is a bad thing) so I'm not trying to dial in a 100% race car either.

ZAPmobile

That's a good idea for the way you say you drive, it will make your track tires last a lot longer.But you will most likely give up some of your handing

hacker-pschorr

It might help because right now I have 235's in the front, 265's in the rear and it understeers like a SOB.

I know I should be able to "fix" that with suspension tweeks. I'm more afriad I'll make it worse. I don't want to find out I setup something wrong half way through the kink....

F451

928 input (don't know why this got moved out of the 928 forum), Chuck Briggs told me recently he is going to equal sized tires/wheels on his race 928 for the very reasons mentioned in that article.

I can't remember if he's going to 10's, or 11's all around.

In any case, he mentioned that with a car that is 50/50 wieight distribution that he felt the car would benefit with the same sized tires/wheels all around.

M758

The point of the article and the point of the post is today's "Fad" is to run wide rear tires and narrow front tires. 911's and high powered mid engine cars need a wider rear tire. However nearly all 50/50 front engine rear drive cars like 928, 944 or the 350Z and many BMW's will do better with the same size tire front and rear. The reason is that adding rear tire adds rear grip which is good, but unless you also add front grip the car will just understeer. For a high performance street cars this is an easy way for the MFG to put a little understeer in a car to make it "safe" for the general popluation.

The other issue is suffing the max rubber under car that further deviates from the front vs rear tire width is not ideal. That is the case on even the RSR, and 430. There is an ideal balance between front tire width and rear tire width and just stuffing the biggest rubber you can get under the fenders is not always the best.

Of course when looking at any racing class the rules must often be taken into account. Rules do limit tire width on the RSR and F430. In cases were tire width is limited like this it is often best to use the widest tire allowed both front and rear even if it means a less than idea mix front to rear. In those cases where a less than idea mix occur you then need to dail the suspension and aligment settings to compensate. Of course this can be complex task.