largest wheel/tire combo on a C3
07-12-2009, 05:31 PM
#21
Intermediate
Member Since: Nov 2008
Location: MN
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Here is what I just did on my 73.
TT II's
Front
17 x 8
4" backspacing
245/45ZR 17 NT555 Extreme
Rear
18 x 9.5
5.25" backspacing
275/40ZR 18 NT555 Extreme
with 18 x 9.5:
You will have to move your ebrake bracket. You may have to shorten your spring by .25-.5"
I'm slightly under the fender using 5.25". 5.5" will put you at the fender lip but gives you more clearance from your spring
TT II's
Front
17 x 8
4" backspacing
245/45ZR 17 NT555 Extreme
Rear
18 x 9.5
5.25" backspacing
275/40ZR 18 NT555 Extreme
with 18 x 9.5:
You will have to move your ebrake bracket. You may have to shorten your spring by .25-.5"
I'm slightly under the fender using 5.25". 5.5" will put you at the fender lip but gives you more clearance from your spring
07-12-2009, 06:14 PM
#22
Race Director
Mine are chrome Coys C5, 18x9.5" with 5 in BS on the back and 17x8" with 4" BS on the front, the back wheels clear the parking brake bracket but I have mine shaved down a bit and every year is different 
Pretty much the way I like it...for now
Pretty much the way I like it...for now
01-31-2018, 10:46 PM
#24
Heel & Toe
Do a search in this forum and the the general C3 forum using "18s" there is hours of reading. It depends on what diameter wheels you want to use and how much you want to mod to get them on. What seems to "bolt on" with no drama is a 17 or 18 by 8 in the front with a 4" backspace and a 245/45 tire. In the rear a 18x9.5 with a 5" backspace and a 275/40-18 tire. Now there are many other combinations that will work and you need to be more specific on what you are looking for (15s - 17s - 18s - ect - ???) to get a more direct answer.
01-31-2018, 11:42 PM
#25
Melting Slicks
Post is about 8 yrs ago !
01-31-2018, 11:57 PM
#26
Race Director
Sorry but it's much easier to discuss backspace rather than offset. In my experience (for what ever that may be worth if anything) when I have measured for custom wheels meaning wheel sizes built to order with various manufacturers (Budnik, Billet Specialties, Team III to name a few) the spec they required was "backspace". Now that was for custom built wheels for specific applications not "off the shelf" pre built wheels. I hope this answers your question as to why I didn't include offset.
02-01-2018, 06:57 AM
#27
Le Mans Master
Member Since: May 2008
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2022 C3 of the Year Finalist - Modified
A lot of SHOCK value though. 
07-28-2021, 11:23 PM
#33
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