czachari

I think that to preserve acceleration I want to keep weight anc circuference down but I want a wider rim for the look and for better handling ( shorter sidewall/wider contact patch ). If I want to keep the stock tires, which rims will be the best fit. Stock rims are 17x7.5. Can I go up to 17x9? Maybe 17x9 rear, 17x8.5 front?

Thanks


CZ

rrf

235 45 17
If you look at the recommendations for that tire: rim max range is from 7.5-9 with optimal being at 8.0

[BTW C32 AMG uses 225 45 17 on 7.5 and 245 40 17 on 8.5 further validating what is said above].

So using that data, you might want to put your 235's on 8's for the front and maybe 8.5 rear. Or maybe better yet, keep the same sizes fore and aft for tire rotation.

If possible, with a 235 I would avoid the two extremes of 7.5 and 9.0 and use either 8.0 or 8.5. If you go too narrow or too wide handling is adversely effected.

BTW a "perfect" 8.5 rim will be able to fit the front, but a 9 is likely to hit the strut or hang out of the fender.

nukblazi

I am running 245/40/17s on 7.5 wheel with no issues. 34 PSI

bajaiman

Do you have any pics of your car using 245/40/17 on your 17" tyres??

amdeutsch

If you are going to use 235/45-17s you will have both speedo- and odometer error. The factory tires have a diameter of 25" and what you want to put on will be 25 1/3".
Small difference I agree but enough to mess with both.

bajaiman

235/45/17 overall diameter is 643.3mm which is 9mm larger than 225/45/17. This is only 1.5% larger than original diameter.
I'm assuming that with larger diameter you'll be travelling faster than what the speedo display, the question is...how much faster?.

Lynn

1.5% faster.

Lynn

What car comes with 235/45 17's as standard equipment? Do you mean 225/45 17? Recommended wheel widths are 7" to 8.5" with 7.5" as best width.

czachari

CZ

Matt230K

cruznlv

Hi Everyone:

I'm new to the forum and nervous about making my first post as everyone here is so knowledgeable about cars. I've been reading this forum for several months now and I've learned quite a bit about my c-coupe, but so much of it is hard to understand since I am new to cars in general.

Anyway, I have a c230k (2002) that I bought used in July '02 with 9000 miles and it came with 18x8 Mille Miglia Evo 5 wheels with Bridgestone Potenza S-03 235/40 ZR18 91Y tires. My question is what should I set my tire pressure to? MB tech at the dearlership and guys at discount tire gave me differing answers. Also, I noticed with sharp right and left turns (like doing a U-turn) that there is what seems like rubbing with my front tires. Is this because my tires are wrong for the wheel or vehicle and is this damaging to the tires? Discount Tire told me the rubbing is minimal and it would be ok to leave it that way.

Thanks.

Matt230K

Hi cruznlv, welcome to the forum! Your problem can easily be fixed. You should trade me wheels. I will gladly take your wheels and tires, and you can have my factory C7 wheels with Michelin tires.

I'm just kidding, unless you would really want to do that. You should not have any rubbing with 18's. There are plenty of people here running 18's and even 19's with no rubbing issues. Although it's hard for me to say for sure that they aren't rubbing. But I would run pressures of 34 or above with 18's. And if you want to get rid of those wheels and tires, let me know.

cruznlv

Hi Matt230K,

Thanks for your nice post. It made me smile and a sigh of relief that I accomplished my first post.

Now I'm wondering if it's not rubbing and something else. But when the wheels were off the car at disount tire, the guy pointed out in the wheel well where the slight rubbing seemed to be, so now I'm confused. Maybe I'll ask the MB tech's opinion at the dealership when I go in for my Service B.

I know, I know, I love my wheels! I think that's what made me fall in love with the car when I first saw it. But if you have C7 wheels that means you have all the other goodies that come with the C7 package, right? Other than two-tone leather (black/grey), I'm barren stock!

Thanks for your post, I'll check my tire pressures tomorrow morning.

tberry

To recap, factory C7 wheels are 17x7.5 and they come standard with 225/45/17s. I have Flik Lex 17x8s with 235/40/17s. According to a tire size calculator (http://www.miata.net/garage/tirecalc.html) my speedo read 2.3% faster than the actual speed. With the new rims/tires the front look perfect (just a tad stick out from fenders) and I put 15mm H&R spacers in the rear (shoulda gone 20mm for more flush look but it looks almost flush as well). Once these tires wear down a bit I'm thinking of putting 245s (dunno 40 or 45s yet any suggestions?).
Also, does anyone know what the handling consequences of putting maybe 245/45/17s in the rear and 225/45/17s in the front?

*Oh and with my current setup there is rubbing when i have about 350lbs of weight in the rear and when the car is traveling above 45mph and a tad bumpy road. But never in cornering or U turns.

rrf

C32 AMG uses 225 45 17 on 7.5 and 245 40 17 on 8.5

AMG thinks this is the best (and in thieir mind "only") way to go.
So you can be sure the handling is really pretty decent.