17" to 18"

S

scarlet-jester

Member
 Christchurch, New Zealand
Giving this some serious consideration currently. My tires are knackered so its time for new boots regardless. I currently have 200s which I am not a big fan of. I have read a few comments on here around this on various threads , but wanted to put this out there for opinions.

Clearly the looks, filling the wheel arch etc. are a given, but what is the consensus on the ride quality, does it degrade noticeably? Would be running non-RF tires.

What do you all think?
 
I’d say you will not notice a difference in terms of ride or comfort changing size but non run flats will feel loads better!
I’m selling some 107s soon if you like the style?
 
Depends, if you're going 17 rfts to 18 non rft you may even think the ride is better. Then consider every tyre brand/model can have a different stiffness sidewall too...
 
Apart from aesthetics, is there any reason you drop the profile of tyres when you go up from 17s to 18s? Given the desire to 'fill' the wheel arch, dropping the profile (to 40) for a square set up only increases the ride height by 1.5mm and the diameter by 3mm. Even with a staggered set up (based on 9" at the back) the difference is even less, circa 1mm with 35s.

Does anybody run 45 on 18" square or 45/40 for staggered?
 
scarlet-jester said:
Apart from aesthetics, is there any reason you drop the profile of tyres when you go up from 17s to 18s? Given the desire to 'fill' the wheel arch, dropping the profile (to 40) for a square set up only increases the ride height by 1.5mm and the diameter by 3mm. Even with a staggered set up (based on 9" at the back) the difference is even less, circa 1mm with 35s.

Does anybody run 45 on 18" square or 45/40 for staggered?
Click to expand...

I think you may be right about the tyre wall height, but don't forget that you've added 25.4mm to the overall diameter because the rims are an inch bigger! So the tyres for the bigger rims have a lower profile to keep the speedo vaguely accurate.

Might be worth having a play around on here:- https://www.willtheyfit.com/
 
Mr Tidy said:
I think you may be right about the tyre wall height, but don't forget that you've added 25.4mm to the overall diameter because the rims are an inch bigger! So the tyres for the bigger rims have a lower profile to keep the speedo vaguely accurate.

Might be worth having a play around on here:- https://www.willtheyfit.com/
Click to expand...

Thanks Mr Tidy - that is exactly where I got the numbers from :). So ride height goes up by 12.7mm and the effective height of the wheel by 2.5cm. Certainly on my car, there is a lot of space above the wheel so I am curious as to whether this is actually doable. And in a literal sense, it will fill the wheel arch out more :D. Is the speedo the prime driver for lowering the profile? I am not overly concerned with that, as long as I know what the difference is mathematically
 
The amount of space you have above the wheel is probably driven more by what suspension you have on your car - the ones with M-Sport suspension sit 15mm lower!

I've got 18" E89 wheels on mine that are the same sizes as the 108s they replaced, but sit much further out as they have different offsets which visually makes them look like they fill the arches better.

I think the speedo is the main driver for the lower profile that BMW use on the sticker on the door pillar!

But many on here (like mr wilks IIRC) recommend a 255/40 x 18 or a 245/40 x 18 rather that the BMW size of 255/35 x 18 on staggered rears as the speedo usually under-reads anyway, so fitting a slightly higher profile actually can make it more accurate. :lol:
 
Mr Tidy said:
The amount of space you have above the wheel is probably driven more by what suspension you have on your car - the ones with M-Sport suspension sit 15mm lower!

I've got 18" E89 wheels on mine that are the same sizes as the 108s they replaced, but sit much further out as they have different offsets which visually makes them look like they fill the arches better.

I think the speedo is the main driver for the lower profile that BMW use on the sticker on the door pillar!

But many on here (like mr wilks IIRC) recommend a 255/40 x 18 or a 245/40 x 18 rather that the BMW size of 255/35 x 18 on staggered rears as the speedo usually under-reads anyway, so fitting a slightly higher profile actually can make it more accurate. :lol:
Click to expand...

Thanks Mr Tidy. I thought mine was an SE but these VIN decoders suggests it has M-Sport suspension
https://bimmercat.com/bmw/EN/vin/decoder/LP17323/EN
https://www.mdecoder.com/decode/lp17323

So this would indicate I don't have quite so much wiggle room to run the higher profiles ....
 
You must log in or register to reply here.
Back
Top Bottom