18" 8.5 and 9.5 tyre size advice needed

patrickbateman · Post by **patrickbateman** » Sun Feb 18, 2018 1:15 am

No answers in the "wheels" section so thought I might as well ask here before giving up,

So I bought the 3SDMS 0.05's and now about to order some tyres for them,

E86 z4c 3.0si

5x120

WIDTH: 8.5" FRONT ET35 offset

WIDTH 9.5" REAR ET40 offset

Goodyear Asymmetric 3 235/40/18 front

Goodyear Asymmetric 3 265/35/18 rear

Is this the perfect size for these wheels please?

Will I encounter any rubbing issues?

Cheers for any advice offered!

Phoenixboy · Post by **Phoenixboy** » Sun Feb 18, 2018 10:08 am

A bit quiet on the forum at the moment
But someone will be along soon to help you out

MrWilks is your man.

mr wilks · Post by **mr wilks** » Sun Feb 18, 2018 1:17 pm

Stock ride height no probs at all op

paulc_bkk · Post by **paulc_bkk** » Sun Feb 18, 2018 1:26 pm

I’m running BBS CH
19x8.5 ET35 with 235/35/19
19x9.5 ET40 with 265/30/19
Toyo non-runflats (I forget the exact model)

I guess this translates to the wheel and tyre specs you are considering at 18” - so hopefully my wheel/tyre spec gives you an idea of general fitment

I think I could’ve gotten away with a 275 on the rear, but there’s not much space for a wider tyre at the front

Standard non-sport suspension, not lowered (yet)

: CE9D909E-4DA6-4F68-B656-5EBB6FB9098B.png (1.15 MiB) Viewed 527 times

mr wilks · Post by **mr wilks** » Sun Feb 18, 2018 1:38 pm

paulc_bkk wrote: ↑Sun Feb 18, 2018 1:26 pmI’m running BBS CH
19x8.5 ET35 with 235/35/19
19x9.5 ET40 with 265/30/19
Toyo non-runflats (I forget the exact model)

I guess this translates to the wheel and tyre specs you are considering at 18” - so hopefully my wheel/tyre spec gives you an idea of general fitment

I think I could’ve gotten away with a 275 on the rear, but there’s not much space for a wider tyre at the front

Standard non-sport suspension, not lowered (yet)

CE9D909E-4DA6-4F68-B656-5EBB6FB9098B.png

Ive known Si coupes have contact on front with 235 35 19 on 8.5s et 35 . Yours i know is a roadster but do you ever have any rub on front liner when having a spirited drive ? as in

into bends with suspension under compression & wheel turned ?

paulc_bkk · Post by **paulc_bkk** » Sun Feb 18, 2018 6:27 pm

I can say I’ve not experienced that yet.....which is not to say that it hasn’t already happened or wouldn’t eventually (not really had the wheels off since they were installed).

My car is pretty low mileage (just over 30,000 miles) so I am suggesting that my setup is a fair representation of most cars, (nor that it’s superior in any way).

I have seen that the gaps at the front don’t have a lot of clearance when stationary/unladen, and it isn’t hard to imagine worn/soft suspension allowing enough travel to make contact when under compression.

Also, I only just noticed that the OP has a Z4C and can appreciate that not all is equal between the coupe and the roadster, so please don’t take my earlier post as gospel.

mr wilks · Post by **mr wilks** » Sun Feb 18, 2018 6:41 pm

paulc_bkk wrote: ↑Sun Feb 18, 2018 6:27 pm
My car is pretty low mileage (just over 30,000 miles) so I am suggesting that my setup is a fair representation of most cars, (nor that it’s superior in any way).

I have seen that the gaps at the front don’t have a lot of clearance when stationary/unladen, and it isn’t hard to imagine worn/soft suspension allowing enough travel to make contact when under compression.

Also, I only just noticed that the OP has a Z4C and can appreciate that not all is equal between the coupe and the roadster, so please don’t take my earlier post as gospel.

Also without being rude

the weight of driver believe or not can make a difference when the numbers are on the tolerance limit

there is a local to me forum member who's a big guy 6ft5ish & a frame to match . He had his car ( 3.0Si E85 Oe springs ) into garage reporting a grating noise at front , mechanic couldn't get it to make any noise so i did a passenger ride with him & i could hear the slight chaff only noticeable when spirited

on compression at drivers side . We swapped places & i drove then the noise transferred to passenger side

he was on 235 35 19 8.5 fronts et35 . Problem now totally gone now he's on 224s

paulc_bkk · Post by **paulc_bkk** » Sun Feb 18, 2018 6:48 pm

True! Skinny blokes ftw

Also noted a typo in my earlier post - meant to say my car is NOT necessarily a fair representation of other cars on the forum (not figured out yet how to edit posts from my phone)

patrickbateman · Post by **patrickbateman** » Sun Feb 18, 2018 11:56 pm

Well I've ordered tonight,

Goodyear Asymmetric 3 235/40/18 front

Goodyear Asymmetric 3 265/35/18 rear

Heres hoping they fit ok,
Thanks to Mr Wilks and everyone else that has helped me out with advice on this, really appreciate it,
I have dyscalculia so working out these sizes is nigh on impossible for me to do on my own, so genuinely thank you for putting up with all my questions,

Z4-forum.com

Z4-forum.com