245's on My R56. Trust Me, I'm a Professional!
 

The R56 has larger plastic over-fender pieces than the R53, and seems to have a bit more tire room as a result. We've previously fitted 235/40R17 on 17x7.5 +45 wheels with no interference...

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We also put 225/35R18 on 18x8 +45 wheels:

Attachment 173991

Those were all-seasons, and it was time to fit some summer tires. I had noticed some downsides to the 225/35R18s. They have very little sidewall -- 225 * .35 = 79mm = 3.1" of sidewall. Plus the 8" wheels were substantially larger than the tire, meaning the edge of the rims were taking a beating from road grit and pebbles, not to mention a curb.

Since the 235/40R17 fits fine, I knew the 235/35R18 would fit fine. But there are only about three offerings in that size, and the cheapest is almost $200 a tire. On the other hand, there was a 245/35R18 in the new Kumho XS, and it was about $30 less per tire. I had wanted to give the Kumho a try anyway -- it's their newest high-performance summer compound. I figured if they didn't work out I could sell the set to one of my Subaru customers.

So we ordered them and mounted them up.

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The good news:

- They have a slightly taller sidewall, at 3.4", so potholes are a little less of a problem.
- They protect the wheel lip much better.
- The grip is ridiculous.
- People love the way the car looks. Strangers stop me and compliment me on it.

The bad news:

- Of course, they don't really fit.

When we fitted the front wheels up, the inside sidewall of the tire was directly on the strut. So we fitted up a 5mm spacer (with longer bolts) to make some room.

Driving around with just me in the car, the tires don't rub under most conditions, but severe suspension compression causes rubbing of plastic on the tire. It seems to be mostly the felty fender liner and a little of the plastic over-fender that's making contact.

With a full load of three kids and their stuff in the car, it rolls fine on flat level pavement, but on any kind of bump it rubs a lot more.

So far it doesn't appear to be hitting anything structural. I'm going to keep my eye out for any actual tire wear. It's a hassle to change tires again, plus I don't really want to shell out the extra $120 for the 10mm narrower size, so for now I'm going to keep them on. But if you're thinking about doing it, I'd strongly suggest the 235/35R18 as a better fit. They should clear everywhere, and they probably won't need wheel spacers in front. That's what I'd go with if I were to do it all again.

Edit: To answer the questions of a couple of people, the car is lowered on our Mach V Technic springs. Stock shocks; H&R rear sway bar.

--Dan
Mach V

i think it'll look better on a clubman running a tad higher ride height and make it look like a crossover suv (Like a FX45).

man 235 35 18? looks clean! what are you dropped on? and you say 235/35/18 should clear everywhere correct? Nothing extra needed.... trying to piece together what I want my mini to look like and your wheel setup is very nice!

Mach V Technic springs.

Correct, it SHOULD clear everywhere. I haven't yet tried it myself, though, so I can't tell you from first-hand experience. And remember that the wheel offset is critical. Don't try to fit 235 with a +35 wheel. It's going to rub.

--Dan
Mach V

what are the specs of the wheels you are running or similar specs that would be able to handle the 235/35/18s?

Rota MC. 18x8 +45. You can squeeze a 235 on a 7.5" wheel, but 8" is better. (The 17" RBs in the first picture in this thread are 7.5" wide, +45.) But the offset is pretty important. If it's too low, you'll start having fender clearance problems.

--Dan
Mach V

Dan:

Would a 235/45/17 on a 17x8 Team Dynamics 1.2 fit without rubbing issues on an 09 Factory JCW? What offset would you suggest?

The reason I ask is that I am going to be purchasing autocross specific rims and tires to run in STX class. That allows for upto a 245, but I figured 235 would be safer. Any long term issues if I were to get the JCW suspension? Let me know your thoughts.

Dan, that looks good - mudflaps and all!

No. The profile is too high. It would have to be 235/40R17.

+45, although I don't think the 17x8 is available in that high of an offset. I'll check on that tomorrow.

I'm not sure what you mean by "long term issues."

--Dan
Mach V

Heh, good eye. I added the mudflaps in a somewhat futile attempt to keep road sand and pebbles from blasting the rear wheels. The edges of the wheel were getting pulverized when the narrower tires were on there. That's not a problem now, since the tires are now beyond the wheel lip.

I do like the look of the mud flaps, though.

--Dan
Mach V

So your wheels would be ET40 now with the spacers?

In front, yes.

--Dan
Mach V

Wow that's odd. How bad was it? I've been running much smaller tires on wider wheels without any signs of wear or damage. The Rota's were having problems with road sand hitting the exposed lip and damaging it?:confused:

3 years running stretch with zero lip damage.

The black-center MC's have black paint that sort of fades into the lip from the back side of the barrel (where the tire covers). That black paint was flaking away where road debris was hitting it, revealing the polished aluminum beneath and giving the appearance of curb rash. There wasn't any actual damage to the wheel, but it didn't look so good.

I think it would not be an issue with the other MC colors.

--Dan
Mach V

what would be the widest tire i could put on 18 x 7 with +40 they are going on a 2008 cooper s

Wheel width is going to limit your tread width. I would not run wider than a 225 on a 7" wheel. Otherwise the tire will look like a balloon on the wheel, and the sidewall will tend to roll over.

--Dan
Mach V

ok thanks i had thought that even 225 would be a bit much, my wife ordered some breyton rims on Tire Rack for fathers day i guess i will make them work ...lol, i wanted a wider rim

Dan,

I know I'll have to measure the exact dimensions of the wheel but I'm wondering in general, can we run 225/45/17's on a set of even stock rims.

I've got a set of 17" Ultraleggras. I don't know the width yet (I'm assuming 7-7.5)

Regardless of the offset (of course, haven't measured that either) is it safe to assume that even with an offset of say (what is normal, 38'ish?) that a set of 225/45/17's would fit?

Obviously, I'll have to measure the exact size of the wheel but I'd like to use a set of 225/45/17's for the track.

Does that sound doable or do I have to have a specific offset?

Thanks for your time.

Mark

EDIT: here is the specs I believe.

Offset: 37mm Backspacing: 5.51" Bolt Pattern: 4-100

The car is an '09 JCW lowered with NM engr'ing springs. Do you think with 37mm offset, I could run 225's for the track?

Orange, OZ only makes 7" wide wheels for our cars. I'd run a 215/45 at the max, as 225/45 is both going to be too wide and way too tall for our cars.

Thanks... I wanted a set of Yokohoma's Advan A048 but they only come in that size (for 17's)

Oh well, I'll look into another brand tire.

Thanks,

Mark

Need help plz: Must replace stock Goodyear Eagle RS-A 205/45R17 84V runflats on 17" Anthracite wheels of my '04 MC40 JCW. Goal is max width but same diameter of all-season runflat on same wheels without spacers & no body/suspension interference. Suggestions? Thx.

Max width tends to be-
215/45-17 (taller than stock)
or
215/40-17 (smaller than stock)
but those are not same diameter as stock 205/45-17.

So if you want the best fitment then try to stick with the stock 205/45-17 size given you have stock sized wheels. If you had wider wheels then more options for wider tire sizes is possible.

Are you sure it will be too wide? Or is it because of the offset?

And the height, you mention will be too tall. I don't see that to be a problem nor actually correct according to tire rack.

A 205/45/17 OEM tire is 24.3" tall.

A 225/35/18 is 24.2" tall... a perfect replacement height-wise.


My only issue is if I can run a 225 with 37 backspacing... anyone verify?

Thanks,

Mark

Well, it will fit on the rim, but a 225/45r17 is recommended for a 7-8.5" and I know on my fathers bmw, it is a pretty tight fit.

A 225/45r17 tire has an overall diameter of 25", rendering it 3/4" taller than stock.

I'm sorry, I'm not sure if you caught it but I changed my tire size....


I was talking about a 225/35-18, not a 225/45-17 any longer.

Mark