Put 17's back on today...weighed while i was at it (and weighed winter Fuchs)

Colby · 03-14-2002, 08:24 PM

I put my "summer tires" on today (hopefully it won't snow again). They are 3 piece forged 17x8/17x9.5 w/ Kumho tires (255-40-17 and 225-45-17). During the winter I use the stock Fuchs (16x6/7) w/ Blizzaks (205-55-16 and 225-50-16). I weighed each wheel while I was at it:

16x6 Fuch w/ tire 39lbs. each
16x7 Fuch w/ tire 41lbs. each

160lbs. total

17x8 w/ tire 51lbs. each
17x9.5 w/ tire 58lbs. each

218lbs. total

Difference of 58 lbs!!!! And these are nice wheels too ($600 each)

Ugggh! And unsprung weight is the last place you want additional weight.

So here is the question I pose: Is the additional width and lower profile worth the extra weight gained? I can tell a huge handling difference, and can't notice a huge reduction in acceleration (actually, its less prone to wheelspin, which is a plus off the line).

The reason I ask is I plan to race this summer and don't know which set of wheels to get race compound tires for....

Colby

masraum · 03-15-2002, 01:00 AM

Not speaking from experience here, but my assumeption ("e" included to make a point

) would be that you could probably go with a really sticky 16" tire, save the weight, and still stick well. If stiction is really an issue for the drive wheels then you could always get a pair of 16x9's and use larger 16" tires.

I believe for the track 16x7 and 16x8 with the stock sizes should handle better than the stock 6's and 7's with the same stock tire sizes, but that's another issue.

spinner · spinner's Garage

Colby,

I have 17s also and I'm sure they weigh a ton compared to the stock Fuchs. I don't race (only DEs) and the wider tires definitely improved the handling since I use Yoko 032Rs which are a compromise tire. If I were to race, I would use the lightest wheels I can get. Depending on the class you want to compete in, you may have to stick with the stock wheel sizes for your model. For non-turbo 911s, this means the 16x6 and 16x7. I believe the tire sizes are free. You can put on 225/50 and 245/45 on these and is fairly common at the track. For the non-stock classes, you most probably want to use the 7s and 8s as suggested by masraum (16x9s would be best but $$$$).
Good luck with your racing

Paul
87 Carrera

RarlyL8 · RarlyL8's Garage

You aught to try going from 205/225s to 255/345s.

Tyson Schmidt · 03-15-2002, 07:32 AM

Use the wider rims and put Hoosiers on them. The Hoosiers are a very light tire, and will make up for the slightly heavier wheel. You have to remember that you are comparing a skinny set to a wide set, so of course the wider will be heavier. A wider set of Fuch's and tires will be heavier too!

If you were going to be driving on a very wet, very bumpy track, I'd say the skinny Fuch's. Otherwise, wider is better!

orbmedia · 03-15-2002, 10:06 AM

Exactly what kind of 17" wheels do you have? The ones that all of the fast racers use in club racing is the Fikse FM-10 because it's right around the same weight as a Fuchs 16" wheel (19#). FM-10 & Hoosier is the current "hot setup" in club racing.

Bill Verburg · Bill Verburg's Garage

The hp cost of rotating weight is highly dependant on where it is. For wheels 10 extra lbs only costs ~1-2 hp(theoretical backed up by dyno tests) On a 100 hp car this may be perceptible, on a 200 hp car not.

The bigger issue with tires is rolling radius. The change from 225/50x16 to 245/45x16 will result in a decrease in loaded radius of ~.1". This tiny decrease can be easily felt in better acceleration.

Conversely a change to 255/40x17 will result in an increase in rolling radius of ~.2" this can also be felt(and measured) in decreased acceleration.

chris krebs · chris krebs's Garage

Colby,

A lot of the weight is in the Kumho's... I think the things are made of lead! Are you club racing or autox? I agree with the other member... get the Hoosiers and go! I run 2 cars, 1 in GT and 1 in IT; I've had Goodyears/Hoosier/Kumho/BFG. Hoosiers are light, stick, and go fast.

APKhaos · 03-18-2002, 11:35 AM

My two sets of wheels are:
Stock 6&7/16 Fuchs and 7&8/16 BBS modulars for track DE.
The wheels are close to equal in weight, with the BBS sightly heavier than the Fuchs.
The tires are another story.
Pirelli P7000 must be one of the lightest street tires around - but the compound is hard, which means less grip and plenty of noise when pushed hard in the corners.
AVS Intermediates are heavier, when normalised for the size differences, but really stick well on the track and are far more predictable at the limits.

Its always a tradeoff!