[VegasG42]

Ordered some 20x9 fronts , and 20x10 rears.

My stockers are, I believe, 19x8 , 19x8.5

Stock front tires are 225s. Which on the 8" wheel have tons of extra meat outside of the rim.

The reasoning for possibly wanting to go with 235/35/20 front and 275/30/20 rear is the identical circumference. 0% difference.

I would prefer a wider front , but that would put me at an either .08% difference , or a 1.1% difference.

This is my first AWD car, so I'm not sure how detrimental these warnings are about not going over a 1% difference.



Would 235s be weak on a 9" wide wheel ?

[VegasG42]

Something else that I have to take into consideration -

Not every tire that is a 275/30/20 , has a 235/35/20 counterpart.

Most brands and tires that fit my criteria , does however typically have a 245 or 255 counterpart.

My criteria being a Summer , ultra performance - up to 189 mph, and non-run flat. As I live somewhere that sees dry conditions 99% of the year.

I wouldn't rule out all-seasons , but I don't need to spend more money for tires that I won't ever be driving in inclement weather.

And I don't really need top of the line $400+ tires either, as I don't track the car.

[VegasG42]

After doing a bit of preliminary research - it now appears 235s are definitely off the table.

These would have a good deal of stretch. Something I don't want. Looks like even 245s on a 9" wheel are barely cutting it.

Might have to look at 255 / 275 or 285s.

[Wasp_Factory]

I had 225 Pirelli fronts on my M240iX from factory and then changed out the standard wheels for custom alloys. I went with the sizing from the optional ZTK package, so 245 at the front and 255 on the rear.

My thoughts are that the steering was quicker with more feedback with the 225s, despite the new alloys being around 9Ibs lighter. Having run the 245/255 set up now for 9 months, I'd say it is plenty of tyre for the car, particularly with Xdrive. Stepping up tyre size adds unwanted unsprung mass and detrimentally affects the steering feel.

So with all that said if you want a decent fast road set up particularly where you live, I wouldn't go too wide on the front - 245 max on the fronts would be fine and is in the sweet spot for a 9" rim.

If you went with 245/35/20 on the front, this would allow you 275/30/20 on the rear at 0.97% delta between front and rear circumference. More than enough tyre, the right widths for the rims, enough sidewall for comfort and performance and acceptable for xDrive. A number of UK tuning companies that went to 20" used this tyre configuration.

As for tyres, the Michelin PS4S is the way to go in my opinion and ideally the star rated version, which has more of the Cup 2 compound. Both the sizes noted above are available (in the UK at least).

[VegasG42]

Originally Posted by Wasp_Factory

I had 225 Pirelli fronts on my M240iX from factory and then changed out the standard wheels for custom alloys. I went with the sizing from the optional ZTK package, so 245 at the front and 255 on the rear.

My thoughts are that the steering was quicker with more feedback with the 225s, despite the new alloys being around 9Ibs lighter. Having run the 245/255 set up now for 9 months, I'd say it is plenty of tyre for the car, particularly with Xdrive. Stepping up tyre size adds unwanted unsprung mass and detrimentally affects the steering feel.

So with all that said if you want a decent fast road set up particularly where you live, I wouldn't go too wide on the front - 245 max on the fronts would be fine and is in the sweet spot for a 9" rim.

If you went with 245/35/20 on the front, this would allow you 275/30/20 on the rear at 0.97% delta between front and rear circumference. More than enough tyre, the right widths for the rims, enough sidewall for comfort and performance and acceptable for xDrive. A number of UK tuning companies that went to 20" used this tyre configuration.

As for tyres, the Michelin PS4S is the way to go in my opinion and ideally the star rated version, which has more of the Cup 2 compound. Both the sizes noted above are available (in the UK at least).

Great feedback, thank you. That was my reasoning as well for not really wanting to do a 9.5/265 square setup. I just don't think we need that much wheel and tire up front. I'm not faulting anyone who runs the square setup, but I would just rather run what I think would be the best overall

And looking at tirerack and also discount tire, for their specs they have 235 listed for a 9-in wide wheel no problem. And the tire shops are usually fairly conservative. So I might just stick with my plan of 235/275. To get 0% circumference difference from front to rear.

[BabyM240i]

Originally Posted by VegasG42

Great feedback, thank you. That was my reasoning as well for not really wanting to do a 9.5/265 square setup. I just don't think we need that much wheel and tire up front. I'm not faulting anyone who runs the square setup, but I would just rather run what I think would be the best overall

And looking at tirerack and also discount tire, for their specs they have 235 listed for a 9-in wide wheel no problem. And the tire shops are usually fairly conservative. So I might just stick with my plan of 235/275. To get 0% circumference difference from front to rear.

I'll be doing 235/275 on a 9 and 10” wide 20” wheel.

[VegasG42]

Originally Posted by BabyM240i

I'll be doing 235/275 on a 9 and 10” wide 20” wheel.

I've decided on the same.

The 0% difference of diameter from front to rear makes it completely worth it , imo.

And as mentioned before , I don't really see the practicality in adding a massive front wheel and tire to the front steer wheels