[XC3LLR8]

I've ordered the ZTK package (performance wheels, etc.) which includes 8.5" and 9.5" wheels. I've always preferred a more meaty tire over anorexic sidewalls in both looks and protection, while knowing you may give up a little in razor-sharp turn-in. With this in mind I've started looking at Michelin Pilot Sport 4S's in plus sizes, while staying within specs of Tire Rack's Rim Width Range.

I couldn't figure out why a 275 would have a more narrow Tread Width than a 255, so I started an online chat with Tire Rack. Turns out BMW will establish tire specs for specific models, and in this case the 275's Tread Width is for new M3's and M4's. I'm guessing when you have a tread width that is significantly more narrow than the rim width it makes initial turn-in feel much more responsive, and this is the effect BMW is going for?

Moral of the story: If you want a tire with more tread, and appears wider, make sure you compare the other same size / same brand options to the ones spec'd for BMW.

When it's time for new tires I'm considering 255/35 for the front, and 275/35 for the rear. Quality spacers will be used for final fitment perfection, just as they will with the OEM tires.

[danallxt]

Thanks for posting
That chart is totally bizarre. I'm assuming the chart is for the tires pictured? Michelin 4S? In which case this is kinda bonkers.

The BMW star 275/35 has a narrower tread width than the 255/35 BMW star tire...makes no sense.

And the stated 6.8 inch tread width for the 245/35 is roughly the nominal tread width of a 205 or 215 tire? What's goin on here?

[XC3LLR8]

Originally Posted by danallxt

Thanks for posting
That chart is totally bizarre. I'm assuming the chart is for the tires pictured? Michelin 4S? In which case this is kinda bonkers.

The BMW star 275/35 has a narrower tread width than the 255/35 BMW star tire...makes no sense.

And the stated 6.8 inch tread width for the 245/35 is roughly the nominal tread width of a 205 or 215 tire? What's goin on here?

Thanks for the correction, I mixed-up a couple of the sizes which I'll try to edit in red.

And yes, really bizarre how much sizes fluctuate within same specs.

The tires pictured are both PS4S in 275, with one a BMW spec and one not. Just a reference to show what to look for when ordering.

[danallxt]

As you referenced in your initial post, i guess BMW is playing around with handling dynamics by having narrower tread width than "normal" on a given rim width.

It just seems weird if one didn't check specs, you could order a 245 tire and get a tread width equal to that nominally provided with a 205 or 215 tire. I've always been aware of subtle treadwidth differences within a given sidewall width but was unaware of such big differences, thanks for posting.

[Jashue]

Thank you for this great service to the community!

[XC3LLR8]

Originally Posted by Jashue

Thank you for this great service to the community!

I really beginning to wonder if TireRack has a dyslexic employee entering this data?

The BMW/non BMW specs for 245 shows 6.8 vs 8.6, and the BMW/non BMW specs for 275 shows 8.9 vs. 9.8.

[danallxt]

Originally Posted by XC3LLR8

I really beginning to wonder if TireRack has a dyslexic employee entering this data?

The BMW/non BMW specs for 245 shows 6.8 vs 8.6, and the BMW/non BMW specs for 275 shows 8.9 vs. 9.8.

I contacted Tire Rack about the weird numbers, they remeasured and found their data for the 275 in error, it should have been 9.8 they acknowledged and they said they would correct the data. They did verify the really really weird number showing for the 245 which i suspect is still an error....6.8 tread width is nominal for a 205 to 215 aspect tire, and strangely the inverse 8.6 is nominal for the 245.

[XC3LLR8]

Originally Posted by danallxt

I contacted Tire Rack about the weird numbers, they remeasured and found their data for the 275 in error, it should have been 9.8 they acknowledged and they said they would correct the data. They did verify the really really weird number showing for the 245 which i suspect is still an error....6.8 tread width is nominal for a 205 to 215 aspect tire, and strangely the inverse 8.6 is nominal for the 245.

Good to hear on the 275. Won't have to worry about remembering to specify certain versions when buying new tires.

And I agree, the 245 has to be an error. No one is going to want a 245 with a narrower contact patch than a 225.