Tyre Options, I've been thinking......

[carrera2RSL]

I am about to fit 295/30 R20 on 11.5 rims and 265/30 R20 on 10.0 rims. Then my plan was to replace with 275/35 PSS and 305/30 PSS. But I have been thinking I wonder if 285/35 Michelin Pilot sport Cup2's on the front and 325/30 MPSC2 on the rear might be possible. Seems the 285's and 325's measure up at 11.4" and 13" wide.

I suspect my edge to edge will be close to 12.5 and 11.0 inches

I will measure my rims tonight edge to edge and the I can guage clearance with the existing tyres mounted on the wider rims

[somer]

guessing 285/35s up front are going to rub or be very close, i think some people run r888s up front on stock rims, but not sure about on wider rims, going to depend on offset.

the best setup going forward (when available) i think are going to be 991.2 GT2RS front tires the MPSC2 N2-generation 265/35/20s and 991.2 MPSC2 N2-generation GT3 305/30/20 rear tires.

if you look at tread width specs porsche always max's them out vs the normal run of the mill spec tires.

[carrera2RSL]

Porsche rim and tyre widths influenced my rim choice the GT3 runs 12x20 with 305/30, they also run 325/30 21 on 12.5x21 for the GT3RS and new GT2. I measured my 11.5 and that are just over 12.5 rim edge to rim edge - 318.5mm so I can see how a 13" width tyre might fit, 305 will be easy

[carrera2RSL]

The fronts were in the workshop, should all be fitted with stock PSS today

Final measurements front rim edge to rim edge 280mm, rear 318.5mm

That's 11" front and just over 12.5 rear. Michelin PSC2's look more interesting now the 285/35 measures 11.4 fitted to a 10 and 325/30 measures 13 fitted to a 11.5

[carrera2RSL]

I have a set of 285/35 and 325/30 on order, I hope they fit. I have measured up and think I will just clear all round.

[M6-Coupe]

What are the offset of your rims?

[carrera2RSL]

10x20 et28 11.5x20 et33

[carrera2RSL]

Looking at the back I have 12mm on the inside from the wheel to strut at the rim edge (this will increase as the circumference increases as the strut point towards the rear parcel shelf) and more at the tyres widest point. The wheels actually measure 318.5mm edge to edge and a 325/30 MPSC2 is quoted at 13" wide on an 11.5" rim (Merc AMG GT R I believe) This is circa 330mm, so this suggests 5-6mm 'bulge' each side. So I should be able to still mainatain 5-6mm clearnance on the inside. The outer I think will be tight, my maths suggest I will be virtually the same at the top of the tyre running 295/30 on 20x10 with 15mm spacers.....

At the front I have yet to measure the inside clearance, but it feels 10-12mm plus from the rim edge and the outside is roomy as well, I think the 2985/35 will easily fit, with 7m extra tyre height and radius I will run close to the inner arch in a few places but should be 100% okay I think ! The quoted size is 11.4 or 290mm my wheel measures 280mm rim edge to rim edge and this is only 5mm try bulge, so easy

[Used2be]

Originally Posted by carrera2RSL

At the front I have yet to measure the inside clearance, but it feels 10-12mm plus from the rim edge and the outside is roomy as well, I think the 285/35 will easily fit, with 7m extra tyre height and radius I will run close to the inner arch in a few places but should be 100% okay I think ! The quoted size is 11.4 or 290mm my wheel measures 280mm rim edge to rim edge and this is only 5mm try bulge, so easy

I will be waiting for your results with interest. I have the BBS 9.5" wheels with 26et in the front and would love to use the 285/35 tire. I'm not as meticulous with my measurements as you are, but with the clearance I currently have with a 275/35 tire it's too close to call. I don't want to go through the hassle of ordering, mounting, and loading the front tire through its full turning travel without driving, in case I have to return it. Best of luck and I hope it works for you!

[carrera2RSL]

Anyone had any issues with DSC and tyre size I have heard that this gave problems on an E92 M3- not sure how much out it was

By size I mean rolling radius

[Northern X5M]

You planning to track this setup?
A 285 SC2 up front is alot of tire.
I am running a 275 PS4S up front and a 305 SC2 rear and it is a pretty nice set up for DD and occasional shenanigans.

I am interested to see how this looks and what the final clearances are.

[m5 guy]

Originally Posted by Northern X5M

You planning to track this setup?
A 285 SC2 up front is alot of tire.
I am running a 275 PS4S up front and a 305 SC2 rear and it is a pretty nice set up for DD and occasional shenanigans.

I am interested to see how this looks and what the final clearances are.

How?s everything in the rain with your setup?

[carrera2RSL]

I think my tyre choice will be poor to average in the rain, seems MPSC2's are much better than MPSC's in the rain, also seems that Michelin evolve tyres without shouting about it. This tyre is off the new Merc AMG GTR, so a track oriented road car. Supposedly great grip in the dry.

My car is an early 2015 and it's only covered 13k as I get the train to work every day and walk to the station. So less of an issue for me, I might regret it !

Evidently cold and wet they are well behind a PSS or PS4s but in the dry and warm temp.....

[carrera2RSL]

Okay some more measurements on the front, I have at least 14-15mm on the inside from the rim edge, 12+ of room to the arm for height. This is from the rim edge which measures 280mm across edge to edge, the 265's are flush with the rim edge if i lay a straight edge across.

If the 285 measures as specced on a 10" rim its 13", so 290mm at its widest, thats only 5mm bulge per side, an easy fit the height should be okay too. I think this will be 'easy !"

[Used2be]

Originally Posted by carrera2RSL

If the 285 measures as specced on a 10" rim its 13", so 290mm at its widest, thats only 5mm bulge per side, an easy fit the height should be okay too. I think this will be 'easy !"

I have to mention your clearance for the tire as it travels through its turning arc on the front. The 285/35 might contact the plastic splash guard in the front. I can't tell from the measurements you post whether you've measured for that? But please, mounting and running them is the surest way to find out! Let us know your results!

[carrera2RSL]

A good point when I looked at the weekend I could see one spot would be tight, I could measure easily, but thoughts that a radius increase of 7mm would be okay as BMW would provide a reasonable clearance

[carrera2RSL]

Thinking back M5-guy fitted 285/30 R21, these are about 5.5mm bigger, so 285/35 will ne 1.5mm more than that

[m5 guy]

Originally Posted by carrera2RSL

Thinking back M5-guy fitted 285/30 R21, these are about 5.5mm bigger, so 285/35 will ne 1.5mm more than that

The spot you have to watch out for is where the bumper connects with the fender. The plastic liners stick out right there and will be what rubs. There is a ton of clearance everywhere else. That is the spot that would occasionally rub under full compression.

It really is the limiting area as the top of the fenders are fine. The wheels still look sunk in even though there is no more space thanks to that section.

[carrera2RSL]

Tks, is this about 1/3 the way up near the footwell about 2-3 inches in from the arch. I did see a lump there

[m5 guy]

Originally Posted by carrera2RSL

Tks, is this about 1/3 the way up near the footwell about 2-3 inches in from the arch. I did see a lump there

Yep that's the spot. The annoying offset compromising spot. Right there on the edge, can feel it with your hand and even look at it when you turn the wheel. Like it's laughing at you...

I never bothered to look underneath it to see why it bumps out like that. if you do let me know.

[carrera2RSL]

Hmmm, I wonder if I'm being too brave with 285/35 and 325/30 's....

[carrera2RSL]

Final decision 375/35 305/30 MPS4S, seems no one was prepared to send two sets on the understanding they would need to be fitted but not driven, I would pay for the extra carriage... No takers

I also spoke to Michelin and they said the reduced wet weather performance and the need for tyre temperature before gains in grip, put the MPS4S, Plus he said a lot of short road miles on MPSC2 is something the tyre dont like and it can end up good on tread but below par on grip. Shame I fancied trying to squeeze in 325/30's