analogmike

I ran my GTA2 car like that for a few years, they work great with 285 front and 305 rear tires, especially the Michelin cup rear. I have an extra set of new CUP-S front fenders is anyone wants to go that way, also a cheap set of '08 Grand Am used fronts but they don't look as cool or work as well as the CUP-S.

Picture is with smaller wheels for rain tires.

mobonic

Mike, what advantages did you feel or get from cup s over grand am package?

analogmike

The Cup S fenders make more downforce and have less drag as they cover the tires. The '08 tires stick out, here is the same car as above, original '08 Grand-Am bodywork:

mikymu

I think your WC has wider rear fender already

Fantastic suggestions to avoid body work!

That's one way to increase front grip with larger front wheels

-----------------------

Thanks for all the useful feedback guys and I have learn alot in the process. BBS motorsport got back to me and they told me the 2010 Cup car have the following wheel specs

7.1 Cup 3 piece BBS wheels
front wheel
outer rim: 1" vs. 1.5" for 7.2 Cup
inner rim 8"

Rear wheel
outer rim 2.5" vs 3" for 7.2 Cup
inner rim 8.5" vs 9" for 7.2 Cup

So the 2010 Cup have the front outer rim width increase by 0.5" and rear outer AND inner rim width increase by 0.5" = 1" increase total per side which expalin the total width increase on the *** by 1.73"

As GT3 Techno suggested that you can just increase inner rim width on the rear to accomodate larger tire. 7.1 Cup front wheel can accept slightly larger 250/65/18 tire. So ... what will your Cup beheave on the track with larger front and rear tires? Let'st take a look at this chart below provided by Justin at Tirepro Flosom

much larger and taller rear wheel with 30mm increase in inner rim will increase offset by 30 mm = increase ride height and camber which will contribute to more understeer. There are number of things you can do to counter this effect such as soften front shock, raise front tire pressure and lower rear tire pressure, soften front sway etc. I am not sure why GT Techno experience drop in tire performance

claykos

Increasing inner rim width doesn't increase the width of the car.

mklaskin

My body is stock, aside from the front Grand-Am fenders which are bolt-on's. Some teams ran wider body work prior to 2010, but 3R was not one of them.

mikymu

Interesting. Perhaps only inner rim width was increased as mentioned by GT3 Techno?

GT3 Techno

Yes and I would need to check my rims to make sure but I think we just changed the 8.5" inner section for a 9" for an total increase in size of only 0.5"

mikymu

0.5" on the inner rim will be enough to fit the larger 300/68/18 tire and really no need to go the full 1" increase. Inner rim cost about $550 each

Glen

Call me before You spend a dime on this....
PM sent

mikymu

Will do Glen!

Thanks

mklaskin

I doubt that this helps very much, but in the photos you can see that my car retains stock bodywork. Glen's car has had the inner fender tubs worked on to allow the taller Michelins. I can't get the 710's to fit.

Talking to Glen is definitely a good idea.

lordpantsington

I love these cars! More/any photos=always awesome.

James-GMG

Mike, yes indeed your WC Cup has the stock bodywork, as we had a 3R Cup in here that was the sister car and it was stock.
In 2009 we widened the rear track and adjusted the wheel inner and outers for both the front and rear and updated the front fenders from the GA1 setup to the Cup S.

I have some bodywork left over for both versions as well as BBS wheels that fit the widebody front and rear.

We did run the bigger 12" rear with stock bodywork on the narrow body 997.1 but we had to adjust the inner and outer halves to make it work with the 305 Toyo we ran back then.