Would 225/45-18 square setup rub on non Z4M Coupe?

[kartman]

Decision time – winter tyres.

Currently running MV2s with 225/40 front and 255/35 Rear on 8 and 8.5 rims, staggered obv.

So if I were to purchase a square set of 225/45-18 tyres (similar to what the Z4M has on fronts - i.e. 45 not 40 profile) would I:
- Have rubbing issues at all? Front or rear fenders on the coupe...
- Would my speedo be totally off wack and I would end up putting too much stress on gearbox?

:headbang:

My reasoning is after my car gets a full nano wax treatment I’ll keep using it in winter so it doesn’t just stand. Old cars should not be left standing. Plus I want a little extra ground clearance from the taller sidewall. What do you guys think? Bad move? Or would be OK? I believe the 8.5 rim will take the 225 tyre on the back with a bit of stretch.

My other option which costs the same, is to get a used set from E90 of 17 in rims with tyres in 225/45-17 sizing. Downside – ground clearance remains low for winter, car looks more donky with 17s. on the upside, less care for 17s in winter, easier to swap…

Thoughts? :tumbleweed:

 

[bigdog]

If you do the plus one/ minus one sizing. Your overall diameter will remain very close to factory. Thus it will not effect your gear box or speedo. I have an 06 Si. I run a set of four 225/45/17 winter tyres. the diameter is 25" which is identical to the summer 255/40/18 - 225/45/18.

 

[kartman]

If you do the plus one/ minus one sizing. Your overall diameter will remain very close to factory. Thus it will not effect your gear box or speedo. I have an 06 Si. I run a set of four 225/45/17 winter tyres. the diameter is 25" which is identical to the summer 255/40/18 - 225/45/18.

i dont think you understood the question. my stock is 225-40 18, looking to go 225-45 18. so profile goes up, similar what m car cas...

i know that whole keepin overall diameter same as you increase rim/reduce profile and vice versa idea, thats staright forward.

to put it differently, sure you can run 225-45-17, but will 225-50-17 rub or not...

 

[bigdog]

Yep. I misunderstood. :slaphead:

 

[kartman]

so guess noone knows here? how could i find out without purchasing 2 sets of tyres?....

 

[bigdog]

Just run the 225/45/17's on a spare set of wheels. Much easier swap out for the change of season. And it's an approved set up as well.

 

[RJS-Z4]

I run //M wheels, with M size tyres, on my 3.0 2003 and it's totally fine.

Hope that helps.

 

[kartman]

Just run the 225/45/17's on a spare set of wheels. Much easier swap out for the change of season. And it's an approved set up as well.

my goal is to slightly increase ground clearance for winter.... so 17s while easier may mean scraping a lot....

 

[kartman]

I run //M wheels, with M size tyres, on my 3.0 2003 and it's totally fine.

Hope that helps.

you got the roadster... you reckon fenders are the same on coupe?

 

[bcworkz]

I'm running the exact same size winter tyres you are considering. No issues at all, even enough room for low clearance cable chains, though they are very hard to install for me and my big hands. (I carry a jack, which gives my hands enough room). I'm 99% certain the fender clearances are the same coupe/roadster. According to my GPS, the OEM setup causes the speedo to read a bit high, with winter tyres the speedo is dead on. The slight added torque will not affect the drive line, in colder weather you're not going to get enough traction to stress the system anyway, even on clean dry tarmac.

 

[RJS-Z4]

I run //M wheels, with M size tyres, on my 3.0 2003 and it's totally fine.

Hope that helps.

you got the roadster... you reckon fenders are the same on coupe?

I don't see why it'd be any different.

 

[kartman]

I run //M wheels, with M size tyres, on my 3.0 2003 and it's totally fine.

Hope that helps.

you got the roadster... you reckon fenders are the same on coupe?

I don't see why it'd be any different.

I come from 7 years in 3 series (e90) and quite clearly learned a lesson that M car wheels have 1) more agressive offset 2) larger diameter wheel overall due to higher profile and 3) to accomodate it all M cars have wider fenders!

So i was thinking if the Z cars and ZM cars have same logic or not. It would appear that ZM cars front bumper fits perfect to non M Z car which means that front fenders are likely to be same. Still, before I spent 800 EUR on tyres Id like to know for sure and dealer obviously wont advise me on putting M sized diameter on non M car because it aint proper.

But ill go for 225/45 18 tomorrow, hopefully the stretch isnt too bad on the 8.5 rim on the rears...

 

[Bing]

The fenders on non M coupes and facelift roadsters are identical. The mounting points for all e85/86 fenders, M or non-M, facelift or prefacelift, are identical. Tbh the second set of wheels option is a good one - I do exactly as Bigdog does. I am not sure and extra 5mm clearance is going to make much difference at all. However, from what others have said your proposed set up will be fine

 

[kartman]

Today ive bought a set of 225/45-18s all around on MV2s staggered. Drives fine so far, much more comfy than stock run flats. The shop of course managed to scratch some rims taking the fking runflats off and goddamn it i cant prove or have the nerves to argue (Or pay the deductable 200 eur). This country is fking useless when it comes to consumer protection laws, but at least free wifi and electric charging points everywhere, yey.

Now gonna look into buying a set of 19s for summer as already have a set of yokohamas lined up from a friend for 300 EUR only... And through the stupid RFTs out.


PS - car LOOKS much nicer on slightly chunkier tyres, much like Z4M does. Happy with that very much!

 

[kartman]

would like to report after additional driving.
light scrubbing on the mid portion of the tyres (forwards probably?) in the front arches on big dips which are driven trhough fast. So basically NO, the setup will scrub at least a little bit so I dunno what you guys been using but thats my feedback. Ill probably keep the tyres for winter to have extra clearance and so on, but in summer will go back to stock sizes.

 

[Finisterre]

I have drilled a few holes through an arch liner then used cable ties around a carefully curved oak sprag to re-shape liners before now.

if you are bothered.

 

[kartman]

I have drilled a few holes through an arch liner then used cable ties around a carefully curved oak sprag to re-shape liners before now.

if you are bothered.

I'm sorry. Instructions unclear, can you PM me exactly what you did or post some pics, like which parts you fixed etc? not looking forward to scrubbing on bumps even if its very minor. I love how comfy car is btw so I dont want to have lower sidewalls in winter.

Instructions needed probably more for my mechanic whom Ill pay to do this, i really cant be bothered to do this myself, you got that right.