[kjb914]

I'm switching over to 295 in the rear and 265 in the front, but I notice that some people put 295/40/21 - and others put 295/35/21 in the rear. Seems like everyone keeps it 265/40/21 in the front.

With the 295/35/21 in the rear and 265/40/21 in the front:

1. Won't you notice a lower profile tire in the rear and not in the front?
2. Won't the shorter tires technically revolve faster and will it mess up the all-wheel-drive?

Thanks!

[SWOT1]

I’m doing the same, 265/40/21, 295/35/21. Less than 1% diff from stock ratio... won’t negatively effect anything (other than slightly heavier tires (may lose .1 sec in drag times), but will improve grip and vastly improve the vehicles’s look/stance, especially in the rear.

[Thewolfbmw]

Originally Posted by kjb914

I'm switching over to 295 in the rear and 265 in the front, but I notice that some people put 295/40/21 - and others put 295/35/21 in the rear. Seems like everyone keeps it 265/40/21 in the front.

With the 295/35/21 in the rear and 265/40/21 in the front:

1. Won't you notice a lower profile tire in the rear and not in the front?
2. Won't the shorter tires technically revolve faster and will it mess up the all-wheel-drive?

Thanks!

I am very curious myself. I know going to a 265/40 on the front it increases the height by .3" and 295/35 on the rear will lower the height by .2".

A 305/35 on the rear would be the closest match for height and diameter, but think it would be to wide. Add on a spacer and I might need an industrial mud flap.

Interested to see what others are doing.

[kjb914]

Originally Posted by SWOT1

I’m doing the same, 265/40/21, 295/35/21. Less than 1% diff from stock ratio... won’t negatively effect anything (other than slightly heavier tires (may lose .1 sec in drag times), but will improve grip and vastly improve the vehicles’s look/stance, especially in the rear.

Awesome, thanks! Not worried about losing .1 Won't matter when I slam a tune in. Plus, like you said, the look is what matters!! Still cant believe it comes stock with such narrow tires

[kjb914]

Originally Posted by Thewolfbmw

I am very curious myself. I know going to a 265/40 on the front it increases the height by .3" and 295/35 on the rear will lower the height by .2".

A 305/35 on the rear would be the closest match for height and diameter, but think it would be to wide. Add on a spacer and I might need an industrial mud flap.

Interested to see what others are doing.

See - this is what I dont understand. I know nothing about tires.. If 265 is the width, and 40 is the height - how does putting 265/40 on the front raise it if 255/40 is what's stock??? Is it because a wider tire is being squeezed on the rim and slightly bowing out the tire???

[MrItaly]

Originally Posted by kjb914

See - this is what I dont understand. I know nothing about tires.. If 265 is the width, and 40 is the height - how does putting 265/40 on the front raise it if 255/40 is what's stock??? Is it because a wider tire is being squeezed on the rim and slightly bowing out the tire???

Simple. 40,unlike the 265 in your example, is not an absolute number. The 265 is a straight measurement in millimeters. The height of the side wall is a percentage of that number--40 percent in the case of your example. One is absolute, the other is a percentage of that absolute.

[kjb914]

Originally Posted by MrItaly

Simple. 40,unlike the 265 in your example, is not an absolute number. The 265 is a straight measurement in millimeters. The height of the side wall is a percentage of that number--40 percent in the case of your example. One is absolute, the other is a percentage of that absolute.

Ohhhhh....got it. Thank you!!

[mjrennie]

Originally Posted by MrItaly

Simple. 40,unlike the 265 in your example, is not an absolute number. The 265 is a straight measurement in millimeters. The height of the side wall is a percentage of that number--40 percent in the case of your example. One is absolute, the other is a percentage of that absolute.

That's really interesting. So a 295 35 would have a wicked profile compared to a 265 40.

My question is how a wheel with a stock, straight from the factory 265 could take on a 295 tyre. Isn't the tyre way to big?

[SWOT1]

295 is the largest/widest to fit on the stock wheel.

(For reference, the M40i has a .5” more narrow wheel, but stock 275’s. No problem getting a 295/35/21 on the X3MC 10" rim... 265f/295r SHOULD be the stock option on the X3MC!!)

[MrItaly]

Originally Posted by mjrennie

That's really interesting. So a 295 35 would have a wicked profile compared to a 265 40.

My question is how a wheel with a stock, straight from the factory 265 could take on a 295 tyre. Isn't the tyre way to big?

The variability really depends on the factory rim/tire combo. In our case, the rear tire width (265) is quite conservative given the width of our rear rims. When viewed vertically, they probably curve slightly inwards meaning they're more on the minimum end of the tire width that could be mounted. A full vertical nuetral width might be around 275 or 285. 295 will probably be wider than the metal rim (someone who's tried this can correct me if I'm wrong),so it won't be a 90 degree vertical rise from rim to edge of tire but will still be within the limits of what can be properly fitted on that rim.

[gatorfast]

Originally Posted by mjrennie

That's really interesting. So a 295 35 would have a wicked profile compared to a 265 40.

My question is how a wheel with a stock, straight from the factory 265 could take on a 295 tyre. Isn't the tyre way to big?

Tires have a range of wheel widths that they will fit on. There is what is called the "measured rim width" which is the optimal rim width that the tire is designed for. However, any given tire will generally fit a width range from 0.5"- 1" smaller or larger than the measured rim width.

For example, the rear 265/40/21 tires on the X3M have a measured rim width of 9.5" but will fit on a wheel between 9.0-10.5" wide. I believe the X3M wheels are 10" wide which is in the 265/40/21 tire fit range, albeit slightly stretched from the 9.5" measured rim width. The 295/35/21 tire has a measured rim width of 10.5" but will fit on a wheel 10-11.5" wide. So the factory 10" wide wheel is within its range, however it is the minimum width needed to safely run that size tire.

[mjrennie]

Originally Posted by MrItaly

The variability really depends on the factory rim/tire combo. In our case, the rear tire width (265) is quite conservative given the width of our rear rims. When viewed vertically, they probably curve slightly inwards meaning they're more on the minimum end of the tire width that could be mounted. A full vertical nuetral width might be around 275 or 285. 295 will probably be wider than the metal rim (someone who's tried this can correct me if I'm wrong),so it won't be a 90 degree vertical rise from rim to edge of tire but will still be within the limits of what can be properly fitted on that rim.

Thank you. I appreciate your knowledge.

[mjrennie]

Originally Posted by gatorfast

Tires have a range of wheel widths that they will fit on. There is what is called the "measured rim width" which is the optimal rim width that the tire is designed for. However, any given tire will generally fit a width range from 0.5"- 1" smaller or larger than the measured rim width.

For example, the rear 265/40/21 tires on the X3M have a measured rim width of 9.5" but will fit on a wheel between 9.0-10.5" wide. I believe the X3M wheels are 10" wide which is in the 265/40/21 tire fit range, albeit slightly stretched from the 9.5" measured rim width. The 295/35/21 tire has a measured rim width of 10.5" but will fit on a wheel 10-11.5" wide. So the factory 10" wide wheel is within its range, however it is the minimum width needed to safely run that size tire.

Thank you.

[bulwhip]

So what are the disadvantages/problems to running a 22" wheel all around?

...or a 20" wheel all around?

There seems to be better wheel choices in those sizes.

[gatorfast]

Originally Posted by bulwhip

So what are the disadvantages/problems to running a 22" wheel all around?

...or a 20" wheel all around?

There seems to be better wheel choices in those sizes.

It's mainly aesthetics and ride quality. Some people prefer the appearance of a larger wheel thus they prefer to run a 21" or 22" wheel over something like a 20" wheel. However, as wheel size increases then tire aspect ratio will decrease (ie a thinner tire) which will reduce ride comfort.

A 20" wheel setup should ride noticeably more comfortable than a 22" wheel setup.

[dunny247]

Originally Posted by SWOT1

I’m doing the same, 265/40/21, 295/35/21. Less than 1% diff from stock ratio... won’t negatively effect anything (other than slightly heavier tires (may lose .1 sec in drag times), but will improve grip and vastly improve the vehicles’s look/stance, especially in the rear.

Need pics once you've done it please.

[SWOT1]

Originally Posted by dunny247

Need pics once you've done it please.

Can't wait to post plenty of pics! Vehicle should be built/delivered by the end of January.

[kjb914]

Ok so here's another question. I havent even looked to see what size the spare is, but lets say I switch over to 265's and 295's and I get a flat tire - can I still put that spare on???

[gatorfast]

Don't think there is a spare

[kjb914]

Originally Posted by gatorfast

Don't think there is a spare

There is..

[SWOT1]

Originally Posted by kjb914

There is..

Mobility kit deletes the spare. (I need the extra cargo space, and not the extra weight for the spare.)

[MrItaly]

Originally Posted by SWOT1

Mobility kit deletes the spare. (I need the extra cargo space, and not the extra weight for the spare.)

+1 FTW!