235/40/18 on 18x8 ET34 - will it rub?

[DaveD]

Hi

Looking at taking the winter wheels of my forged 18x8 405m wheels of my f30 330d and trying a square set up on my coupe. Looking to go MPSS.

Offset is ET34, so 13mm more poke than standard wheels at the front/16mm at back. M sport suspension so not low. Know they’ll be fine with 225/40/18 at the front but will 235/40/18 rub? Not a huge difference but don’t want to chance it. Know tears will be fine

Cheers

D

 

[mr wilks]

If i was a betting man id say yes it will rub slightly but only on full compression or full lock it will be down to just a few mm & even the difference between brand new rubber (8mm) & part worns (4mm) can sometimes make the difference especially with et34 .
That said there are a few members running 8j et 34 fronts ( MV3s) so worth hearing their thoughts on tyre sizes to confirm

 

[DaveD]

Thanks Mr Wilks. I’ve got a 15mm spacers on at the moment and no rubbing with 225/40/18 but it’s getting pretty close.....

 

[mr wilks]

Thanks Mr Wilks. I’ve got a 15mm spacers on at the moment and no rubbing with 225/40/18 but it’s getting pretty close.....

Switching up to 235 40 18 on the 8j effectively reduces arch gap by 4mm then consider a full tread Michelin which are a wide fitting tyre (Falken / Hankook narrower ) & it will be borderline .

 

[Mr Tidy]

Not exactly the same, but I'm running style 295s off an E89 on my Coupe with standard Sport suspension.

Fronts are 8Jx18 with ET29, but I've got 225/40 Bridgestone Potenza's on them. But with ET29 that's 5mm further out than an ET34, and a 235/40 is only going to sit 2.5mm further out than a 225 would. While a 234/40 will have a bit more sidewall. it'll only be 40% of 10mm more, so I would have thought it might be OK.

I've had them on the car 6 months now, and no rubbing at all.

Good luck anyway.

 

[mr wilks]

Not exactly the same, but I'm running style 295s off an E89 on my Coupe with standard Sport suspension.

Fronts are 8Jx18 with ET29, but I've got 225/40 Bridgestone Potenza's on them. But with ET29 that's 5mm further out than an ET34, and a 235/40 is only going to sit 2.5mm further out than a 225 would. While a 234/40 will have a bit more sidewall. it'll only be 40% of 10mm more, so I would have thought it might be OK.

I've had them on the car 6 months now, and no rubbing at all.

Good luck anyway.

Either your tyres are on the wearbars or you must never drive with any spirit ive had the very same set up re width / offset & rolling radius on 2 different E86 Si , one lowered , one stock & both had a chaffing ( strangely only ever on drivers side :? ) when hitting twists / dips / bends at speed . Not enough to wear the liner away but noticeable to hear it

 

[Mr Tidy]

My tyres are probably less than half worn, but I definitely do drive it with spirit - that's why I've got it!

Maybe I've just been lucky not to hit the right sort of dip with the driver's side wheel! :lol:

I certainly don't get any rubbing on lock.

 

[mr wilks]

My tyres are probably less than half worn, but I definitely do drive it with spirit - that's why I've got it!

Maybe I've just been lucky not to hit the right sort of dip with the driver's side wheel! :lol:

I certainly don't get any rubbing on lock.

Bridgestone runflats have sloped shoulders , its part of the runflat design so that will aid you & not heard Berkshire being known for its great driving roads so that too my drive is on a slope , if i reverse on full lock with car angled then i can get rub , driving off no rub , its very marginal & what can be got away with on one car may not on another even though same model . spec .

 

[brillomaster]

hmmm slightly worried now... i was going to fit some MV3s to my e85, but my track tyres are a 245/35/18 on the front... work fine with MV1s, but will MV3s get some rubbing? :?

 

[Mr Tidy]

Bridgestone runflats have sloped shoulders , its part of the runflat design so that will aid you & not heard Berkshire being known for its great driving roads so that too my drive is on a slope , if i reverse on full lock with car angled then i can get rub , driving off no rub , its very marginal & what can be got away with on one car may not on another even though same model . spec .

That's the problem - it seems to vary from car to car and each brand of tyres adds another variable!

We do have some good driving roads in Berkshire (admittedly not loads) but you just need to know where they are.

 

[patriot66]

I run a staggered set of MV3s on my Zed, 225/40R18 et34 8J on fronts and 255/35R18 et37 8.5J on rears. I had quite bad rubbing on the front top outside wheelarch liners on high speed compression bumps...it wore through the plastic I changed my Sport springs back to SE and fitted new Bilstein B4s and it has never rubbed since. Also the front Avon ZZ5s have quite a narrow and square shoulder which probably helps too. This is how the car sits now

 

[DaveD]

I run a staggered set of MV3s on my Zed, 225/40R18 et34 8J on fronts and 255/35R18 et37 8.5J on rears. I had quite bad rubbing on the front top outside wheelarch liners on high speed compression bumps...it wore through the plastic I changed my Sport springs back to SE and fitted new Bilstein B4s and it has never rubbed since. Also the front Avon ZZ5s have quite a narrow and square shoulder which probably helps too. This is how the car sits now 20190314_224228.png

Interesting. When I was running 20mm spacers up front on my OE wheels I did get rubbing (went slightly through the drivers front arch liner too) on sport springs. Back to 15mm spacers now so pretty close to ET34 now and no rubbing. That’s with 225/40/18 Michelin PS4 rubber. MPSS is a slightly squarer profile than the MPS4 from memory (had them before) so I guess even at 225/40/18 there is a risk of rubbing. I’ve got just under 2 degrees of camber up front with pins pulled. Guess I’ve always got the option of camber plates to give a bit more.

As an aside, is a hole in the wheel arch liner going to cause an issue at MOT? I’m looking for a spare on eBay but just interested.

 

[philbo909]

hmmm slightly worried now... i was going to fit some MV3s to my e85, but my track tyres are a 245/35/18 on the front... work fine with MV1s, but will MV3s get some rubbing? :?

You'll get a lot of rubbing

 

[ErrErrminator]

I run a staggered set of MV3s on my Zed, 225/40R18 et34 8J on fronts and 255/35R18 et37 8.5J on rears. I had quite bad rubbing on the front top outside wheelarch liners on high speed compression bumps...it wore through the plastic I changed my Sport springs back to SE and fitted new Bilstein B4s and it has never rubbed since. Also the front Avon ZZ5s have quite a narrow and square shoulder which probably helps too.

Whereas my car, on sport springs and standard shocks (I think), is running exactly the same wheel size/tyre size/offset combo and I have not had any issues with rubbing at all. Not sure I'd get away with 235 tyres up front though.

 

[brillomaster]

hmmm slightly worried now... i was going to fit some MV3s to my e85, but my track tyres are a 245/35/18 on the front... work fine with MV1s, but will MV3s get some rubbing? :?

You'll get a lot of rubbing

hmmm might give it a go and see... I'm not lowered, just standard SE springs I believe. patriot66's car looks great!

I could always revert to a 225/40/18 when I next need new tyres - the fronts probably have 3 trackdays left in them.

 

[philbo909]

hmmm slightly worried now... i was going to fit some MV3s to my e85, but my track tyres are a 245/35/18 on the front... work fine with MV1s, but will MV3s get some rubbing? :?

You'll get a lot of rubbing

No harm in trying if you own the tyres already, don't go buying a new set though :lol:
hmmm might give it a go and see... I'm not lowered, just standard SE springs I believe. patriot66's car looks great!

I could always revert to a 225/40/18 when I next need new tyres - the fronts probably have 3 trackdays left in them.

 

[DaveD]

Quick update. I’ve had the 405Ms on for a few weeks now, with 225/45/18 sottozero runflats! Tyre pressures reduced to 30F/32R. Have put 15mm spacers on rear but will reduce to 10mm as pokes out a bit too much for my liking (runs completely flush with wheel arch).

There is no rubbing front or rear.

I have been genuinely impressed with this set up even with runflat winter tyres! Balance is much improved and rear end much more playful. Grip levels are surprisingly high so would be better still with MPSS. The extra sidewall does definitely help to improve the drive. More positive steering response and less twitchy, feels more planted over rough ground. I quite look the big tyre look too but if I’m honest that is secondary to finding the best b road set up I can.

Need to get some proper tyres next. Thinking 225/45/18 MPSS or 235/40/18 MPS4. Decisions decisions...

Pics below.