Upto date answers? on Rear 261 Rim Fitment?

[dh58]

I've searched around and can't find any good upto date answers on this.

What is the widest tyre that can fit on the stock 261 rear rims?

I'm looking at getting either 255, 265 or even 275. However nothing I have found has been able to answer what will fit well.

I am going wider for better traction.

[Fakemike]

These are the recommended specs from TireRack with Michelin PILOT SUPER SPORT. I'm looking at the "Rim Width Range" column.





The rear 261 rim is 8.5 in wide. So they are saying 255 is the largest. But I would think a 265 would be okay.

Warning: I'm not a tire expert.

[juld0zer]

I wouldn't go too wide unless this is for drag use only. Late generation tyres have very thin and soft sidewalls so the balloony floaty feeling from fitting too wide tyres will only get worse.

I'd say the stock rears are best fitted with 255 wide but not all 255 wide tyres are identical in dimensions. A 245/35-18 looks perfect on M135i rears which are 8" wide but the same tyre on a 261m rear rim looks slightly stretched.

[135]

Legally, the widest that can be fitted to an 8.5" wide wheel is a 255/35/18 tyre.
If it's for the track then whatever your game with putting on. Personally, I wouldn't go wider than 255s though and, on the track (circuit), I run a 255 on a 9" wheel on the front. Get suitable width/offset wheels.

In general, 275/35/18 can scrub, especially on the fuel filler pipe, if using incorrect offset wheels - the OD of a 275/35/18 is too tall.

Also, if you do decide to run wider than a 245 on an 8.5" wheel, the section width will reduce by 5mm for every 0.5" the recommended wheel size for that tyre is greater than the target wheel because you're squeezing a wider tyre onto a smaller wheel (it pulls the tyre bead in), e.g.
The recommended wheel size of a 255 is 9", which is 0.5" more than the 8.5" target wheel, therefore, the section width of a 255 will be reduced by 5mm when fitting on an 8.5" wheel.
The recommended wheel size of a 265/275 is 9.5", which is 1.0" more than the 8.5" target wheel, therefore, the section width of a 265/275 will be reduced by 10mm when fitting on an 8.5" wheel.
The opposite applies for fitting a too-narrow tyre on a wider than recommended wheel.
Note that advertised section widths can vary by 1-2mm to actual/measured section width and tyre manufactures can update tyre specs to vary the section width over time (as I have found).

Don't forget that an 8.5" wheel is not 8.5" wide! It's actually ~9.5" wide (very, very close to it). This is because the advertised wheel width does not include the wheel flanges, which adds ~0.5" to each side. Therefore, you should match a tyre's section width to the actual/measured wheel width, e.g. my 255s now have an advertised section width of 257mm on a 9" wheel but an actual section width of 259mm when actually fitted to my 9" wheels and, for an additional data point, an actual section width of 254mm (252 calculated advertised) when actually fitted to my 8.5" wheels - proof the "5mm for every 0.5" difference" is valid. I have the same type of results for various other tyre/wheel width combinations.

[titium]

Originally Posted by 135

In general, 275/35/18 can scrub, especially on the fuel filler pipe, if using incorrect offset wheels - the OD of a 275/35/18 is too tall.

all depends on the tyre I destroyed my fuel filler neck (massive hole in it) with 255/35/18 pirelli p0's on stock 261m wheels.

was a nice surprise at the petrol bowser.....

[vtl]

Originally Posted by titium

all depends on the tyre I destroyed my fuel filler neck (massive hole in it) with 255/35/18 pirelli p0's on stock 261m wheels.

was a nice surprise at the petrol bowser.....

Yep, stuck in the middle of tasmania with no fuel filler neck...

Garden hose and funnel ftw

[vtl]

I'm running 255/35/18 Yokohama AD08R, no issues with rubbing with stock ET52 8.5" wheels

Sidewall is stiff so feels great compared to other bulgey tyres. The shoulder is very square so maximizes the contact patch. Much more grip and traction than most 275 width tyres. You're better off getting a good compound tyre vs trying to squeeze more width in.

[Giveway74]

you start to lose feel and response if the tyre is too wide for the rim.
+Change of direction is not a crisp.

You will see most new performance cars have a little bit of stretch rather than ballooning.

[glendo]

I'm rocking 255 rears... Michelin PSS. no problems at all so far. Will be changing to Michelin PS4's when their time is up.

[walkie86]

I was trying to find 245/35/18s RE003s for my 269Ms (identical spec to 261Ms) but apparently Bridgestone don't bring them in, so I've gone with 255/35/18. Getting fitted tomorrow as part of the buy 3, 1 free deal (FWIW getting 225/40s on the front).

Currently I have worn 255/35/18s on my 130i (hub is 10mm further in) and have no rubbing issues.

[dh58]

After reading everything I think the consensus is 255 is the safest max on the 261.. Going any higher involves risk. I'm really trying to get more traction. I can't launch in 1st, even 2nd I can't put my foot entirely to the floor.

After reading everything, my next question is. At the 265 if the risks had to be weighted and ranked.
1- Rubbing outer (fender rolling)
2- Rubbing inner (fuel filler neck special)
3- Section width limitations (265 isn't actually 265, it's going to be slightly smaller and baloon out?)
4- add in your own?


@135 onpoint advice man. Thank you for that.

Originally Posted by glendo

I'm rocking 255 rears... Michelin PSS. no problems at all so far. Will be changing to Michelin PS4's when their time is up.

Do you mean PS4S or PS4?

If its the 4S, where are you getting them from?

If its the PS4, why are you choosing them over the PSS?

Originally Posted by vtl

Yep, stuck in the middle of tasmania with no fuel filler neck...

Garden hose and funnel ftw

daymmmmm that sucks! HAha because of this I was under my car today checking lol.

[titium]

Originally Posted by dh58

After reading everything I think the consensus is 255 is the safest max on the 261.. Going any higher involves risk. I'm really trying to get more traction. I can't launch in 1st, even 2nd I can't put my foot entirely to the floor.

have you addressed the rear subframe bushes issue?

guide rods and toe arms help alot, more so in keeping the car straight (and more predictable) when they do start spinning. with these mods in my car i have no issue with traction control fully off and having to worry about the car kicking to one side off the line, tracks dead straight even in the wet.

A proper alignment with less then -2deg camber (-1.5 works well) helps also. I've also found 34psi tyre pressures works best with the street tyres I've tried (pirelli p0, bridgestone re003).

I have to agree with vtl after driving his car the grip from the ad08r's is phenomenal.

[dh58]

Originally Posted by titium

have you addressed the rear subframe bushes issue?

guide rods and toe arms help alot, more so in keeping the car straight (and more predictable) when they do start spinning. with these mods in my car i have no issue with traction control fully off and having to worry about the car kicking to one side off the line, tracks dead straight even in the wet.

A proper alignment with less then -2deg camber (-1.5 works well) helps also. I've also found 34psi tyre pressures works best with the street tyres I've tried (pirelli p0, bridgestone re003).

I have to agree with vtl after driving his car the grip from the ad08r's is phenomenal.

No i haven't addressed it yet but I think you and vtl know whats up since I took a look and you've done alot of work there. I am trying to keep mine as stock looking as possible so is any of what you're suggesting going to make it look modified? Also what would be the best bang for buck mods in this area?

And wow 34psi! I run 41 and played with 44?

Also I think our mods are slightly different. Before I went 100% e85+FBO+inlets my traction issues were minimal. Now they are pretty severe. Are you running FBO+e85?

[glendo]

Originally Posted by dh58

Do you mean PS4S or PS4?

If its the 4S, where are you getting them from?

If its the PS4, why are you choosing them over the PSS?
.

I bought PSS rear's because I couldnt find PS3's around in the right sizes. I think they stopped making them for the impending PS4 arrival. I have put new PS4's on the fronts, and my PSS's have passed half-life.

PSS's are amazing grip tyres, but their optimum phase of life-span is a little too short. Im happy to go back to PS4 when they die.

[Dackelone]

Originally Posted by 135

Legally, the widest that can be fitted to an 8.5" wide wheel is a 255/35/18 tyre.

Legally it depends on the country you have the car registered in. Technically speaking... bmw(and the German TUV) say a 245 rear tire is the max width for an 8.5 inch wide wheel. But we all know a 255 tire will fit just fine.

In fact bmw does install a 255 rear tire on 8.5 wide wheels for some of the 3er and X3 models. But everytime I go to get new tires here in DE... the tire shops throw a fit when I tell them I want a 255 rear tire. The only way I am allowed to do it... is bc my car doesn't go thru TUV, I have US cover plates thru the US Army.

So... to answer your question... 255's are really the limit. Perhaps you could go slightly wider... but for sure you will have rubbing issues. The 255's rub for a few days when new anyways. Then all is good.

Dack

[juld0zer]

Oh man, that filler neck damage is gold! Pzero have that almost triangular shaped 'rim protector' bulge. The runflats are even worse but Pzero in 245/35-18 or 255/35-18 and their 19" cousins all have the triangle shaped sidewalls. That's probably what munched your filler neck. Michelin PSS in the same sizes are quite square on the same rims. AD08 are very square.

A good alignment is crucial to getting good front or rear grip. Toe makes a huge difference in rear grip. I had issues with PSS lighting up the nanny light too frequently after i fitted BMW performance springs and Bilstein B8 shocks. Turns out alignment was all over the place. I've since fixed that, rear camber now at -2* and a little extra toe from spec. Totally transformed the car and i'm still re-adjusting from the hairy couple of months i've put up with.

Is your car manual or auto?

I also have Whiteline subframe bushes though.

PS4S is not available in 18", no?

[135]

Originally Posted by titium

all depends on the tyre I destroyed my fuel filler neck (massive hole in it) with 255/35/18 pirelli p0's on stock 261m wheels.

was a nice surprise at the petrol bowser.....

Wow! Sounds like something wrong with the setup. Considerably lowered? Coupled with a large amount of negative camber? I don't even see how that could cause an issue with the +52 offset of the 8.5" 261 though.

The P-Zero 255 has a 257mm section width but only a 224mm tread width, i.e. it has a very rounded shoulder. When fitted to an 8.5" wheel, the section width is only 252mm, so it's even narrower than at first glance.

As vtl mentioned, the AD08R is a very square tyre so, if anything, it should have issues with rubbing. The 265 has a 269mm section width on a 9.5" wheel (274mm on 10") and a 262mm tread width, while the 285 has a 284mm section width on a 10" wheel (and 279mm on 9.5" - as square as can be!) and 279mm tread width. Notice that there is only 10mm difference between the AD08R 265 and 285 when fitted to the same width wheel, which means 5mm less on both the inside and outside. With the 285s on an 18x10" (with appropriate offset), -2.7° camber, guard rolling and pulling and coilovers set at a suitable ride-height, even the 285 tyre didn't rub through the fuel filler pipe. The OD for 255s are around 6mm more than that of the 285, which means 3mm more encroaching on the fuel filler pipe - that might explain it rubbing through but I doubt it - 3mm would make that much of a difference, especially when the AD08R is so square and the P-Zero isn't even close, not to mention the 32mm width difference going from a 285 down to a 255 (252 on 8.5mm, 257mm on 9"). With an AD08R 265 on 10" and 6mm taller OD (i.e. only 3mm top-side) than the 255 (and 14mm taller OD, 7mm top-side, than the 285), still no issues - and why would there be when it's moved 5mm further away from the fuel filler pipe.

I've only read about 275/35/18 tyres on appropriately offset wheels rubbing through the fuel filler pipe so maybe your car setup has some other underlying problem that caused it.

[titium]

Originally Posted by 135

Wow! Sounds like something wrong with the setup. Considerably lowered? Coupled with a large amount of negative camber? I don't even see how that could cause an issue with the +52 offset of the 8.5" 261 though.

The P-Zero 255 has a 257mm section width but only a 224mm tread width, i.e. it has a very rounded shoulder. When fitted to an 8.5" wheel, the section width is only 252mm, so it's even narrower than at first glance.

As vtl mentioned, the AD08R is a very square tyre so, if anything, it should have issues with rubbing. The 265 has a 269mm section width on a 9.5" wheel (274mm on 10") and a 262mm tread width, while the 285 has a 284mm section width on a 10" wheel (and 279mm on 9.5" - as square as can be!) and 279mm tread width. Notice that there is only 10mm difference between the AD08R 265 and 285 when fitted to the same width wheel, which means 5mm less on both the inside and outside. With the 285s on an 18x10" (with appropriate offset), -2.7° camber, guard rolling and pulling and coilovers set at a suitable ride-height, even the 285 tyre didn't rub through the fuel filler pipe. The OD for 255s are around 6mm more than that of the 285, which means 3mm more encroaching on the fuel filler pipe - that might explain it rubbing through but I doubt it - 3mm would make that much of a difference, especially when the AD08R is so square and the P-Zero isn't even close, not to mention the 32mm width difference going from a 285 down to a 255 (252 on 8.5mm, 257mm on 9"). With an AD08R 265 on 10" and 6mm taller OD (i.e. only 3mm top-side) than the 255 (and 14mm taller OD, 7mm top-side, than the 285), still no issues - and why would there be when it's moved 5mm further away from the fuel filler pipe.

I've only read about 275/35/18 tyres on appropriately offset wheels rubbing through the fuel filler pipe so maybe your car setup has some other underlying problem that caused it.

have you ever actually looked at the p0 tyre? the sidewall literally bubbles outward it is the worst for fitment. camber was set at -1.8deg nothing crazy at all.

I've since changed to bridgestone re003 done about 10k km including a track day doesn't even touch the filler neck (put tape over it so it would be obvious if it rubbed).

hancook rs3's just touch it to mark the tape but not enough to wear through any of the tape - pulled the tape off in one piece with no holes in it no issue.

[135]

Originally Posted by dh58

No i haven't addressed it yet but I think you and vtl know whats up since I took a look and you've done alot of work there. I am trying to keep mine as stock looking as possible so is any of what you're suggesting going to make it look modified? Also what would be the best bang for buck mods in this area?

And wow 34psi! I run 41 and played with 44?

Also I think our mods are slightly different. Before I went 100% e85+FBO+inlets my traction issues were minimal. Now they are pretty severe. Are you running FBO+e85?

I think 40+psi is too much, even on the street, and the over-inflation is probably partly contributing to your lack of traction.
I run 36psi on the street and F32psi/R33psi hot (F23-25/R25-26psi cold) on the track for my AD08Rs - cold pressures are track-dependent.
Yokohama specify a very narrow range for AD08R tyre pressures on the track, irrespective of the car weight or tyre size: 32-34psi. And they're spot on. Other tyre manufactures may provide similar indications for their street/track tyres.

[Dyno Junkie]

Stock wheels on our 135i with 225/40/18 & 265/35/18 tyres.
These have been on for almost 40,000k's

[dh58]

Originally Posted by Dyno Junkie

Stock wheels on our 135i with 225/40/18 & 265/35/18 tyres.
These have been on for almost 40,000k's

love it lol... in the end I went with 255/40/18

[dh58]

Originally Posted by 135

I think 40+psi is too much, even on the street, and the over-inflation is probably partly contributing to your lack of traction.
I run 36psi on the street and F32psi/R33psi hot (F23-25/R25-26psi cold) on the track for my AD08Rs - cold pressures are track-dependent.
Yokohama specify a very narrow range for AD08R tyre pressures on the track, irrespective of the car weight or tyre size: 32-34psi. And they're spot on. Other tyre manufactures may provide similar indications for their street/track tyres.

Very good point. I will lower them tomorrow and give them a go.