I'm looking at a set of 18 inch wheels and tires, Anyone know if these will fit a 997.1 turbo?

Front:
18 x 8.5 w/40 offset, with 235/40r18 tires

Rear:
18 x 12 w/45 offset, with 315/30r18 tires.

 

the tricky part is not changing the overall height of the wheels/tires as not to throw off the awd computer.

 

I don't mind changing the tires, mostly interested in the wheel fitting with this diameter and offset.

 

18s will fit on non CCB cars, however as i stated, the available tire sizes in 18 will throw off the height ratio and could trip the AWD Ecu.

 

305 35 18 and 235 45 18 works well on the TT.

The sizes you posted are goin to be 1" shorter which will hurt top end speed.
Is this for road race or drag race.

I think the 26.5's will LOOK more fitting
The 25.5 sizes you posted may look tiny

Those size and offset you posted will work, you could even still pop a 10mm spacer on the rear to flush it out

 

Are you running these size wheels? I am asking as according to my calculations these tires throw off the Front/Rear ratios and can cause issues with the PTM and the transfer case.

Cheers.

Bob

 

Thanks for all the responses.

I'm not running these tires,
i'm looking at a set of 18 inch wheels and tires that are for sale and was interested in if they will fit.

So it looks like I can run these wheels but not the tires.

Does anyone have or know of anyone running 18's?
think it will look odd?

 

It doesn't look odd, just different than stock. Those tire sizes are definitely off though with the front being .4 inches smaller than the rear. You want the rear to be slightly smaller than the front to prevent issues with the stability system kicking in.

 

Nick, yes 18" will fit a 997 Turbo. I have the same wide body car as you but as a GTS. I track a lot and we have a group of Turbo's that all run 18" wheels. Here are the specs you need with tire sizes that work:

9x18 et50 offset 50-53 works
12x18 et48 offset 47-48 works

245/40/18 front and 305/35/18 rear are same overall diameter as stock 19" sizes
255/3518 front and 315/30/18 rear are .5 overall diameter smaller but keep the front to rear ratio same as stock so that your AWD and ABS/PSM doesn't mess up. This size effectively gears the car down for great acceleration and lower center of gravity.

With 315 rear you need a wider front tire than 235. Also 1010tire.com has a great offset calculator so you can put in stock wheel width and offset and see how other offsets affect inner and outer clearances. However I know for a fact that the offsets I posted work on wide body 997 cars.

hope this helps!

 

WOW, AWESOME!!!!

Thanks for the information,

Gotta love 6-speed.

 

Actually, you want the F/R ratio to be right around 97%, so the fronts need to be smaller. This is based on the stock tire diameter/radius calculations. The tolerance on that ratio is quite small, however, the sizes recommended by mdrums will work.

Cheers.

 

still sporting OEM lugs?