Confused about offsetI am looking at buying a set of Team Dynamics Pro Race 1 (17X7) wheels for SCCA solo II "G" Stock class. my stock offset is 50mm. the new wheel is 45mm. Can I run legal with these wheels? Should I use 5mm spacers to bring the offset up to 50mm? I could sure use some advice here. Thanks.

 

17x7 is an OEM size, but all the OEM offsets are either +50 ET or +48 ET... I'm not sure if offset makes a difference...

 

Using a spacer would make the offset less, not more. So using a +45 offset wheel with a 5mm spacer would be like using a +40 offset wheel. Think of the spacer as extending the hub mounting face toward the center of the wheel, if you extend it far enough you get to "0", extend it further and you get to a negative offset instead of a positive offset.

If some of the OEM MINI wheels are 17x7, +48 then you could legally use a +42 wheel.

 

Thanks for the info on the spacers. My '02 MCS was originally equipped with the "sport package" R85 S Lite wheels which have a 50mm offset. (correct me if I am wrong) This being the case, wheels with a 45mm offset would leave a 5mm diffrence. Under the +/- .25 inch (6.35mm) rule, this should leave me within a 1.35mm margin of compliance. Have I got this right?....Anyone?

 

You got it, but why do you want 17's?

Dump the 17's and go with a 16's. R compound tire choices are better.

The only 16's that will work are $$R's or Rota Slipstreams 16x6.5 et45.

 

Thank you all for your input. I have chosen to stay with the 17's for stock class until I sort the car out further. If I go to STX,, and join the mod club, 16's will definitely be on my list.
JD

 

16x6.5 would keep you in stock while being lighter and even quicker gearing.

 

Right, it doesn't really matter what came on your car for it to be stock class legal, what matters is what was available or what could have come on your car. My HS MC came with 15" wheels stock, but since 16's were an option, I'll be using 16x6.5 wheels for racing.

-Keith

 

But unless your getting larger brakes why would you go up to a 16? Wouldn't you want 15 for the same reasons the other guy would go down to 16?

You can probably find some 15's in the 12lb range (Rota Slipstream and the R-Compounds would be cheaper, no?

 

As far as rolling diameter, some 17" tires are about the same as 16's. Yes, a 17" wheel is heaver, but not by much, and larger brake fitments would be no problem. Lastly, a 215 width can be used w/o a problem. Seems like a draw to me. Is there any one out there with some track time on 17's that could give use your input here.

 

I have to use stock width wheels, in this case 15x5.5". I haven't seen any after market 15x5.5 wheels, and even though the stock holey wheels are light at 12 lbs each, squeezing a 205mm wide tire on a 5.5" wide wheel isn't making use of all the rubber available. That's what I did last year though, I got a set of spare stock wheels and put some used 205/50-15 Kumho 710's on them, and they were fine for local competition, but I have some 16x6.5" Enkei wheels in my shop waiting for race tires for use this year. Running 215/40-16 tires on a 6.5" wheel puts a lot more rubber down than a 205mm wide tire on a 5.5" wheel, and has been proven faster time and again on an autocross course.

-Keith

 

Ahhh! I didn't know the stockers were 15x5.5. Yea good choice to go up to the 16's.