would this switch work....
the turboS stock 18" wheels have
front- 18 X 8.5 with 50 mm offset
rear- 18 X 11 with 45 mm offset

New aftermarket 19" wheels have
front -19X 8.5 with 52 mm offset
rear-19 X 10 with 52 mm offset and add 1" spacer to rears

 

drbill,
the front wheel u have now should be 18 x 8 with 50mm.

the 19'' u have will fit but not perfect. u have room in the front & rear to make it look better. what kind of wheel are they? i wouldn't recommend it though since the rear is too narrow for the TT. what tire are u going to run?

 

i would stay aways especially since the offsets are all wrong for the car...

 

Stock turbo S wheels look best.

 

i am adding a 1 in. spacer to rear 19 X10,s. The tires are Continental Exclaim 235-35-19 front and 275-30-19 rear. will the 52 m offset on the 19's be a problem?

 

Dr. why would you down grade your new 06 tt to a 275 rear tire and 10" wide wheels when yours are 295 and 11" ..the car is gonna look really weird ... for that you should of bought a narrow body ..lol....spacers bad news ...!!!!

 

Yes, if you can't resist and must mod.... do it right!

Prior to '02 the 996 came with 265/35/18 rear rubber and 8" wide front rims. After '02 they came with 285/30/18 rear rubber and 8'5" front rims. I think 8.5" front sport designs were originally GT3 fronts. Nathan with the yellow 996 had the GT3 front sport designs. Anyways, they all use the same rear rim, same size, offset, and can take either size rear tire. However, Porsche recommends that you don't change to the wider rear if you have the narrow fronts and if you do, you also change the front rims because even that slight change will alter the handling characteristics of the car and cause the car to understeer more.

Imagine what you will do to your car if you take 1" off the rear rim width. My guess is oversteer!

 

I'm w/ them, while a 1" difference may not be noticeable, most people go wider when they upgrade, not smaller

You've also got two board sponsors telling you not to do the wrong thing.

 

Dr its not about the spacer your actually down grading the car by taking away tread and contact patch .. you might even throw your traction light just because of the lesser contact patch you have ...your rolling diameter is a lot lesser now and your awd system needs it to be within specs if you want to get technical ...remember cheaper route sometime cost the more !!!

 

the rear 19" wheels with 1 in spacers (spacers used commonly- i know someone with 2 in spacers on a 360 spider) will bring the wheel out for brake clearance and flush with wheel well. As far as compromising contact patch and contact i beg to differ. The stock rear 18's are 11x 18 with 295/30/ZR18 with 45 mm offset. The wheels i purchased are 19 in - 19 x10 with 275/30/19 . If you do the math , the side to side tire ratio is not compromised . An upgrade to a 19 wheel/tire with a 275/30/19 has approx. a 300 mm side to side tire ratio. The smaller stock 18's with the 295/30/18 has approx. a smaller side to side tire ratio.You cannot forget the tire ratio/radius increases with a larger wheel. The factory tire ratio was 38.25 with stock 18's and it will now be a radius of 39.85 with the 19's
The company's rep i purchased the wheel/tire pck from has been doing the same setups on turbos for 9 yrs and guarantees his product. He also worked for Champion Porsche before that....

 

sounds like u know what u're getting. go for it then.

 

Id go with new 235 front and 315 rears and keep the 18 in. size but get 18x8.5 and 18x11. Just my 2 cents but it rides, looks and handles better than stock. If buying new wheels get the offsets to push out the wheel not spacers. I do think several are running spacers with no problems. You will need new lug nuts with spacers. It's your car so its your decision.

 

Bill - as a friend I can publically say this ...... you are a bi-polar car nutjob

Leave the TT "s" stock I am fed up with saying I told you so to you after every car!

This Statement is purely out of love
PS - I relinquish my duties as your car advisor after reading these posts wink wink

 

Doc, you need to find a new company rep and your math is wrong. The numbers are as follows.

1st number 275=mm of tire from sidewall to sidewall across the tire
2nd number 30=% of that number that represents sidewall height
3rd number 18 or 19=diameter of rim in inches.

275/30/19 = contact patch of 275mm
295/30/18 = contact patch of 295mm (about an inch wider)

Taking it one step further,

295/30/18 tire has a diameter of 24.96 in and circumf of 78.4 in
275/30/19 tire has a diameter of 25.49 in and circumf of 80.1 in

Taking it even one step further,

295/30/18 = 808 revs/mi
275/30/19 = 791 revs/mi

Speedo difference of 2.1% too slow. Your speedo will read 60 mph when you are actually traveling 61.3 mph.

Therefore people with an 18" wheel/tire combo will do what is typically called a "plus 1" configuration where they go with a larger 19" wheel but wider tire and lower aspect ratio to maintain the same rollout. What you are doing is a "minus 1 configuration" which is pure lunacy. In other words, you are sacrificing performance for appearance and that's not a good idea. It's not about the bling when you have a Turbo S.

 

I forget to mention. The correct plus 1 configuration would be a 305/25/19 tire on an 11" rim.



295/30/18 tire has a diameter of 24.96 in and circumf of 78.4 in
275/30/19 tire has a diameter of 25.49 in and circumf of 80.1 in
305/25/19 tire has a diameter of 25 in and a circumf of 78.6 in

Taking it even one step further,

295/30/18 = 808 revs/mi
275/30/19 = 791 revs/mi
305/25/19 = 807 revs/mi

On a 275/30/19 tire the speedo difference is 2.1% too slow. Your speedo will read 60 mph when you are actually traveling 61.3 mph.

On a 305/25/19 tire the speedo difference is 0.1% too slow. Your speedo will read 60 mph when you are actually traveling 60.1 mph.

In addition to upsetting the handling balance on your car by decreasing the contact patch by 1", consider this additional info before pulling the trigger. It sounds to me like your rep is doing a good job of "selling" you those rims and tires.