[RFGuy_KCCO]

Originally Posted by danniexi

i know this is an old post but why the hell would you put rear tires to the front, especially OEM designated tires?

Looks and handling. It's a very common mod:

https://x3.xbimmers.com/forums/showthread.php?t=1796142

[danniexi]

Originally Posted by RFGuy_KCCO

Looks and handling. It's a very common mod:

https://x3.xbimmers.com/forums/showthread.php?t=1796142

and I've already replied on the thread asking others if the * 265/40 tires are for the front or rear. no one has bothered to find the answer. no one has bothered to answer if the MO1 are front or rear tires as well.

generic 265/40 should be fine, but it's a stupid idea for people to replace the front tires with the rear 265/40.

[Kevin_The_Clean1]

Originally Posted by danniexi

and I've already replied on the thread asking others if the * 265/40 tires are for the front or rear. no one has bothered to find the answer. no one has bothered to answer if the MO1 are front or rear tires as well.

generic 265/40 should be fine, but it's a stupid idea for people to replace the front tires with the rear 265/40.

Why is it a stupid idea to have tires with a slightly wider contact patch & that are a touch more compliant over rough pavement put on the front... ? Do tell.

[danniexi]

Originally Posted by Kevin_The_Clean1

Why is it a stupid idea to have tires with a slightly wider contact patch & that are a touch more compliant over rough pavement put on the front... ? Do tell.

I've never said it was a stupid idea to put a wider tire at the front. I said it was a stupid idea to put a REAR-specific tire to the front. There's a difference.

Given the same size specifications, OE tires can vary widely when it comes to rubber composition and design, given their functionality and purpose. A front tire may have a different ratio when it comes to the outdoor shoulder rubber and the inner shoulder wet compound. The tread design will vary as well, especially for a rear vs front tire. Front tires will most likely have wider longitudinal channels for better wet weather performance, preventing aquaplaning while also reducing the chance of tramlining. Rear tires may have more of a square contact patch with thinner channels which is great for grip and stability, but not for steering (possible uneven wear) and, again, wet weather performance.

Upon further research, it seems like Michelin doesn't even make a "generic" 265/40/21 tire or either that I can't seem to find it on tirerack. They only have two OEM spec tires, the * (BMW) and the MO1 (Mercedes). The * is obviously the rear tires for the F97/8, whereas the MO1 is the front tires used in the GLC63 AMG.

Personally, for safety reasons alone in inclement weather, I'll be going with the MO1 setup.

... funny enough I went through this same thing with the F80 platform. I went with CanAutM3 recommendation and had MPSS 265/35 MO1 and 295/35 * R19 tires (albeit on aftermarket wheels). Probably the single best mod when it comes to actual street driving performance.

[Kevin_The_Clean1]

Originally Posted by danniexi

I've never said it was a stupid idea to put a wider tire at the front. I said it was a stupid idea to put a REAR-specific tire to the front. There's a difference.

Given the same size specifications, OE tires can vary widely when it comes to rubber composition and design, given their functionality and purpose. A front tire may have a different ratio when it comes to the outdoor shoulder rubber and the inner shoulder wet compound. The tread design will vary as well, especially for a rear vs front tire. Front tires will most likely have wider longitudinal channels for better wet weather performance, preventing aquaplaning while also reducing the chance of tramlining. Rear tires may have more of a square contact patch with thinner channels which is great for grip and stability, but not for steering (possible uneven wear) and, again, wet weather performance.

Upon further research, it seems like Michelin doesn't even make a "generic" 265/40/21 tire or either that I can't seem to find it on tirerack. They only have two OEM spec tires, the * (BMW) and the MO1 (Mercedes). The * is obviously the rear tires for the F97/8, whereas the MO1 is the front tires used in the GLC63 AMG.

Personally, for safety reasons alone in inclement weather, I'll be going with the MO1 setup.

... funny enough I went through this same thing with the F80 platform. I went with CanAutM3 recommendation and had MPSS 265/35 MO1 and 295/35 * R19 tires (albeit on aftermarket wheels). Probably the single best mod when it comes to actual street driving performance.

I see what you're saying now & thank you for explaining. I have the 265/40 + 295/35 M01 setup all around. But I would like the get the * setup from the MP4S & use a square 295/35 setup soon (if it fits with spacers). If it's good enough for the X5M & can fit then it should be excellent for our F97/F98.

[CanAutM3]

Originally Posted by danniexi

I've never said it was a stupid idea to put a wider tire at the front. I said it was a stupid idea to put a REAR-specific tire to the front. There's a difference.

Given the same size specifications, OE tires can vary widely when it comes to rubber composition and design, given their functionality and purpose. A front tire may have a different ratio when it comes to the outdoor shoulder rubber and the inner shoulder wet compound. The tread design will vary as well, especially for a rear vs front tire. Front tires will most likely have wider longitudinal channels for better wet weather performance, preventing aquaplaning while also reducing the chance of tramlining. Rear tires may have more of a square contact patch with thinner channels which is great for grip and stability, but not for steering (possible uneven wear) and, again, wet weather performance.

Upon further research, it seems like Michelin doesn't even make a "generic" 265/40/21 tire or either that I can't seem to find it on tirerack. They only have two OEM spec tires, the * (BMW) and the MO1 (Mercedes). The * is obviously the rear tires for the F97/8, whereas the MO1 is the front tires used in the GLC63 AMG.

Personally, for safety reasons alone in inclement weather, I'll be going with the MO1 setup.

... funny enough I went through this same thing with the F80 platform. I went with CanAutM3 recommendation and had MPSS 265/35 MO1 and 295/35 * R19 tires (albeit on aftermarket wheels). Probably the single best mod when it comes to actual street driving performance.

^ This

[mills2424]

Originally Posted by Kevin_The_Clean1

Why is it a stupid idea to have tires with a slightly wider contact patch & that are a touch more compliant over rough pavement put on the front... ? Do tell.

I’m just confused on why he thinks just because that is the size on the rear that it makes it rear specific?

[allinon72]

Originally Posted by mills2424

I’m just confused on why he thinks just because that is the size on the rear that it makes it rear specific?

Because Star spec tires are designed specifically for the vehicle and the rear has a different compound mix than the front. Realistically a non-issue driving the car below 8/10ths, meaning non-track driving.

[Kevin_The_Clean1]

Originally Posted by mills2424

I’m just confused on why he thinks just because that is the size on the rear that it makes it rear specific?

These are the M01 spec not the * spec. So technically these are designed for the front & rear of the vehicle. I hope you don't report me to the tire police.

[spta97]

What the hell is a rear specific tire?

I get it for a funny car but how is this applicable to the X3M?

[richard in NC]

Originally Posted by spta97

What the hell is a rear specific tire?

I get it for a funny car but how is this applicable to the X3M?

Since the X3M rear tire is a different size than the front, Michelin does a BMW spec 255 for the front and a BMW spec 265 for the rear. Michelin engineers have said BMW usually has specific noise and wet handling specifications to meet but I don't think anyone can say just what the difference between standard and * spec are, or any specific spec difference front to rear. I can tell you I've seen different numbers of groves or even different tread patterns!

IMO, based on forum feedback, a * spec 265 (or standard spec) mounted on the front and a standard spec 295 rear seems to work OK but I don't think a Michelin or BMW engineer has tested/certified that combo. I'd still try it if I were on 21s. I may see if I can do that with the factory 20" rims.

PS: I do have connections with current and former Michelin folks. I may be able to get more details. But I was unsuccessful getting the difference between PS4S and PS4 SUV (although the later is "for SUVs but retains PS4 handling") and is what I was forced to get on 20s.