Help - new wheels and tires?

mrlightyear · Post by **mrlightyear** » Tue Apr 05, 2022 8:08 pm

Hi all,

So recently got my e86 coupe, currently on 19” style 108, with bridgestone potenza runflats. I want to say with 225 and 255. And that’s about all I know at this point.

Rides pretty stiff and was just gonna swap out the runflats…but thinking and been advised to go back to oem spec of 18”.

Guess I’m asking what the best wheel and tyre combo for driving on crappy U.K. roads?

Cheers

Mr Tidy · Post by **Mr Tidy** » Tue Apr 05, 2022 8:45 pm

If they are OE Style 108 split-rim wheels they are staggered 18" wheels. 8J x 18 front and 8.5J x 18 rears. OE tyre sizes were 225/40 front and 255/35 rear with Bridgestone run-flats.

Swapping to non-runflats ought to improve the ride, but some SE models had 17" wheels so tracking down a set of those would be another option. You can't go smaller than 17" because all 3.0 Si models have bigger front brakes than other models.

mrlightyear · Post by **mrlightyear** » Tue Apr 05, 2022 8:57 pm

Cheers for the feedback, I’ll need to check then if it on 19” was told by dealer was 18 but then the mechanic that serviced it after said was in 19”…?

Sorry 8j?

Mr Tidy · Post by **Mr Tidy** » Tue Apr 05, 2022 9:49 pm

108s are definitely 18" - my previous E86 had them when I bought it.

"8J" simply defines the width of the rim, so 8" wide. Staggered means the front and rear rims are different widths and 108s are 8" front and 8.5" rear, which is why the rear tyres are wider.

mrlightyear · Post by **mrlightyear** » Tue Apr 05, 2022 10:13 pm

Mr Tidy wrote: ↑Tue Apr 05, 2022 9:49 pm 108s are definitely 18" - my previous E86 had them when I bought it.

"8J" simply defines the width of the rim, so 8" wide. Staggered means the front and rear rims are different widths and 108s are 8" front and 8.5" rear, which is why the rear tyres are wider.

Ah how’s does that relate to the 225 and 255 for the tyres?

Is going wider than standard a thing? What are the pro and cons?

Mr Tidy · Post by **Mr Tidy** » Tue Apr 05, 2022 10:29 pm

mrlightyear wrote: ↑Tue Apr 05, 2022 10:13 pm
Mr Tidy wrote: ↑Tue Apr 05, 2022 9:49 pm 108s are definitely 18" - my previous E86 had them when I bought it.

"8J" simply defines the width of the rim, so 8" wide. Staggered means the front and rear rims are different widths and 108s are 8" front and 8.5" rear, which is why the rear tyres are wider.
Ah how’s does that relate to the 225 and 255 for the tyres?

Is going wider than standard a thing? What are the pro and cons?

The standard tyre sizes are 225/40 front and 255/35 rear. The rears are wider because the rear wheels are 0.5" wider than the frons.

The second number as in "40" or "35" is the profile of the tyre as a percentage of the tread width. So a 225/40 has 225mm width of tread and the sidewall is 40% of 225mm.

The rears have 255mm tread width and a sidewall that is 35% of 255mm - that way the overall diameter of the tyre is pretty much equal to the fronts.

MikeyH · Post by **MikeyH** » Tue Apr 05, 2022 11:12 pm

I think my back tyres are 245 /40 on 18” wheels. Does this cause problems. The car is an e85 2.2se with m sport 224 wheels. Fronts are 225/40

Mr Tidy · Post by **Mr Tidy** » Tue Apr 05, 2022 11:47 pm

MikeyH wrote: ↑Tue Apr 05, 2022 11:12 pm I think my back tyres are 245 /40 on 18” wheels. Does this cause problems. The car is an e85 2.2se with m sport 224 wheels. Fronts are 225/40

Don't confuse the OP!

224s were the standard wheel for the M models and have different sizes and offsets - OE tyres also had different profiles.

Staggered 18s for non-Ms like 108s, MV2s, 107s, etc. were 8J ET47 fronts with 225/40 tyres and 8.5J ET50 rears with 255/35 tyres.

224s for Ms were 8J ET42 fronts with 225/45 tyres and 9J ET30 rears with 255/40 tyres.

mrlightyear · Post by **mrlightyear** » Wed Apr 06, 2022 4:42 am

Okay okay think I’m starting to get all this… again thanks all!

Now is there any advantage, disadvantage of going wider than stock?

sars · Post by **sars** » Wed Apr 06, 2022 8:41 am

Wider tyres with the same profile equate to a larger contact patch, equals more grip and more road noise but a higher and more comfortable sidewall. You should also consider that a larger diameter and wider tyre may have issues with scuffing the wheel arches, a larger diameter rear wheel will also reduce acceleration and change actual speed vs indicated speed.

If you change alloys you need to consider offset and bolt circle diameters, Mr Tidy kindly indicated your offsets

enuff_zed · Post by **enuff_zed** » Wed Apr 06, 2022 8:45 am

Just for a little clarity, Everyone is telling you the tyre size, but the obvious point is, if you look at the tyre it will say something like 225/40 R 18.
That last figure is the wheel diameter, so you can be exactly sure what you have on there.
A picture would help.

mrlightyear · Post by **mrlightyear** » Wed Apr 06, 2022 9:30 am

Again thanks all!

Confirmed they are 18s, 225/40R18 & 255/35R18.

My goal here is to improve the ride quality as she’s pretty stiff and feel every bump on the road and possibly reduce the tire noise, so looks like I’m off to get the wheels refurbished and fit non run flats. As currently on Bridgestone runflats.

Been recommended Michelin tyres, want to say PS4 if I remember correctly - any recommendations?

I’m under the impression that the oem Bwm wheels are made bbs?

When buying the car had intended on getting csl wheels but the 108 have grown on me a lot. Guess I’m curious are there “108” made by a different manufacturer that are better (presume lighter) than the bmw/bbs ones?

Cheers!

sars · Post by **sars** » Wed Apr 06, 2022 9:48 am

mrlightyear wrote: ↑Wed Apr 06, 2022 9:30 am Again thanks all!

Confirmed they are 18s, 225/40R18 & 255/35R18.

My goal here is to improve the ride quality as she’s pretty stiff and feel every bump on the road and possibly reduce the tire noise, so looks like I’m off to get the wheels refurbished and fit non run flats. As currently on Bridgestone runflats.

Been recommended Michelin tyres, want to say PS4 if I remember correctly - any recommendations?

I’m under the impression that the oem Bwm wheels are made bbs?

When buying the car had intended on getting csl wheels but the 108 have grown on me a lot. Guess I’m curious are there “108” made by a different manufacturer that are better (presume lighter) than the bmw/bbs ones?

Cheers!

The 108's are indeed manufactured for BMW by BBS (but not all BMW alloys are manufactured by BBS), a split rim design that many on here love, refurbishing them properly is a little more expensive as they have to be split (undo all those little cap head screwed around the edge). Personally, I don't think they suit the coupe at all.

If you are after comfort, rather track performance then the Michelin PS4 are subjectively better than PS4S as the sidewall is slightly stiffer, a cheaper option would be Goodyear F1 A5's or the new Continental SportContact 7. One thing on here if you ask someone for a tyre recommendation you will get many to choose from, from Goodride ditch finder 2's to Michelin Pilot Cup 2's as we all have our preferred choice, the ones we just bought, because we all want our opinions validated

A great source of information on tyres is https://www.tyrereviews.com/Article/202 ... e-Test.htm

tiglon · Post by **tiglon** » Wed Apr 06, 2022 9:59 am

The SportContact 7 is an ultra high performance tyre and so it is an alternative to the MPS4S not the MPS4. Not a good choice if you want to reduce noise or increase comfort.

sars · Post by **sars** » Wed Apr 06, 2022 10:48 am

tiglon wrote: ↑Wed Apr 06, 2022 9:59 am The SportContact 7 is an ultra high performance tyre and so it is an alternative to the MPS4S not the MPS4. Not a good choice if you want to reduce noise or increase comfort.

Ah those that criticize, the OP asked for suggestions on a quieter tyre than the Potenza's, he did not ask for the quietest possible tyre, ergo the SportContact 7's are certainly a few decibels quieter than what he is currently running

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