Quick Tire Size Check

[jimmy3530]

Hi everyone:

I'm interested in a new sets of wheels for winter for my 2000 C4 996 which currently has the stock 18" chrome turbo twists on it. I am pretty sure the sizes are:

Front: 225/40/18 7.5J x 18 50 mm offset

Rear: 265/35/18 10J x 18 65mm offset

I see a set for sale from a 2008 997 and they are:

Front: 235/40/18 8J x 18 ET 57

Rear: 295/35/18 11J x 18 ET 51

Can anyone confirm or deny that they would fit my car. I love the Carrera III five spoke design and would like to upgrade from my turbo twists.

Thanks

[balefire]

I have the same wheels and tires.

although they fit my mk2, the rear wheels will not fit your mk1.

[jimmy3530]

Excuse my ignorance, but what are the mk2 and mk1? Exactly how will the rear wheels not fit? Too wide or is it an offset problem.

Thanks in advance.

[balefire]

Mk1 1998 to 2001

Mk2 2002 to 2004

The rear suspension changed for mk2 that allows a wider or more offset wheel.

That wheel will rub on the outside of the tire with your fender in the rear

[Long Islander]

997's have taller tires. Your current tire heights are 637.2mm/642.7mm (fr/rr). The height of the front tires you're thinking of is 245.2mm (about a third of an inch too tall). The rear is 663.7, which is nearly an inch too tall.

If you are thinking of discarding the tires and buying the correct size tires (245/40 front and either 285/35 or 295/30 rear), I think the front should work with a 7mm or possibly wider spacer. The offset on the 997 front wheel is 7mm less positive than your current wheel. That means it will stick out 7mm less, which is easily corrected with a spacer and longer lug bolts.

The rear offset is also less positive, by 14mm. That could be cured by a 13mm or 15mm spacer and longer lug bolts (I don't think there is a 14mm spacer). The tire size that is recommended for that size wheel with a 245/40 front is 295/30. There is a Porsche technical bulletin that states that an 11x18 63mm offset wheel with a 295/30 tire on a MK1 996 "may" rub the fender lip (and therefore require fender rolling). However, I have gotten confirmation from a few 996 MKI owners with stock suspension that they had no rubbing issues without rolled fenders. Some have used 11x18 wheels with 285/35s with no rubbing issues, but that will result in a height of 628.2mm vs. 634.2mm, making it a bit shorter than it should be.

The reason I know all this is because I ordered a set of Porsche Sport Techno wheels (with 18x11 ET 63) and had concerns about 295/30 rears rubbing. I'm still waiting to get one more rear wheel that isn't blemished before I can mount my new wheels and find out whether they rub in the rear.

Hope this helps.

[balefire]

NO spacer will correct the wheel offset in the rear on those carrera 3s.

however, 997 tire size works fine on a 996 provided the wheel is the correct offset and width.

[jimmy3530]

Thank you so much for all this information. I'm thinking that maybe I should just stick to a 996 wheel combo and forget about spacers, bolts, and mods.

[jimmy3530]

Found another set of the same tires! I really love the 5 spoke design and I like the fact that they are not chrome as on my 2000 C4

So, the new set are the same as the other ones I found (I guess people don't like them):

235/40/18 ET 57

295/35/18 ET 51

Interersting how Oggie says the correct tire fitment is 245/40 and 295/30.

So, if I buy these I'll need a 7mm spacer up front and 13 mm spacer in the rear. Can anyone confirm this?

Thank you!

[balefire]

Found another set of the same tires! I really love the 5 spoke design and I like the fact that they are not chrome as on my 2000 C4

So, the new set are the same as the other ones I found (I guess people don't like them):

235/40/18 ET 57

295/35/18 ET 51

Interersting how Oggie says the correct tire fitment is 245/40 and 295/30.

So, if I buy these I'll need a 7mm spacer up front and 13 mm spacer in the rear. Can anyone confirm this?

Thank you!

I guess I wasn't very clear in this thread.

The front 997 wheels and tires WILL FIT with a 7mm spacer.

The rear 997 wheels and tires WILL NOT fit your mk1 996.

The rear wheel WILL RUB the fender unless you do the following:

1) extreme negative camber which will probably cause premature inner tire wear

2) roll the fenders which can damage the paint.

As I said before NO spacer will fix the rear wheel offset.

99% people would NOT get that wheel tire combo for their mk1 996.

Edited March 14, 2013 by balefire

[jimmy3530]

Balefire...thank you for the clarification. Very helpful. There is just one thing that I still don't get. Hopefully this doesn't come across as obtuse....

Fronts:

Got it...I need a 7mm spacer to bring the offset in line with my current OE setup. No questions.

Rear:

Is the issue one that my current wheel is 10 inches wide versus the 11" wide wheel that I want to buy. It's not a tire issue then? I figured that mounting the correct tire size (295/30) and playing with the offset would work. What if I go with 285's.

I guess I have to keep looking for the Carrera I wheels made for the 996

Thanks again.

[pfbz]

Hi everyone:I'm interested in a new sets of wheels for winter for my 2000 C4 996 which currently has the stock 18" chrome turbo twists on it. I am pretty sure the sizes are:Front: 225/40/18 7.5J x 18 50 mm offsetRear: 265/35/18 10J x 18 65mm offsetI see a set for sale from a 2008 997 and they are:Front: 235/40/18 8J x 18 ET 57Rear: 295/35/18 11J x 18 ET 51Can anyone confirm or deny that they would fit my car.

--

The front 997 wheels and tires WILL FIT with a 7mm spacer.The rear 997 wheels and tires WILL NOT fit your mk1 996.The rear wheel WILL RUB the fender unless you do the following:1) extreme negative camber which will probably cause premature inner tire wear2) roll the fenders which can damage the paint.As I said before NO spacer will fix the rear wheel offset.99% people would NOT get that wheel tire combo for their mk1 996.

Another data point...I recently purchased a set of OEM take off 997 Carrera III wheels and tires for my 996 C2, so far working out great. The ones I picked up were 10x18RO58 on the rear, which is the same width with 7mm *less* offset than my stock 996 Carrera II's, which is perfect for the rear. The fronts were 8x18RO57, which as mentioned above, really need at least a 7mm spacer.Are the wheels you were looking at (11J x 18 ET 51) wide body wheels? You should be able to get 11" wide wheels to work, but you are going to want ~63mm offset to fit a narrow body 996. Edited March 15, 2013 by pfbz

[balefire]

Balefire...thank you for the clarification. Very helpful. There is just one thing that I still don't get. Hopefully this doesn't come across as obtuse....

Fronts:

Got it...I need a 7mm spacer to bring the offset in line with my current OE setup. No questions.

Rear:

Is the issue one that my current wheel is 10 inches wide versus the 11" wide wheel that I want to buy. It's not a tire issue then? I figured that mounting the correct tire size (295/30) and playing with the offset would work. What if I go with 285's.

I guess I have to keep looking for the Carrera I wheels made for the 996

Thanks again.

Although some people can run a skinny tire to solve this problem, that is not a good solution.

http://www.1010tires.com/Tools/Wheel-Offset-Calculator

There are plenty of other 996 and 997 wheels that have a better offset to fit your NB mk1 996.