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[PKT RKT]

Curious if the 255/40 + 265/40 combo will work on an E92 wearing 18x9.5 et22 APEX wheels?

- 265/35 is kinda short versus 245/40
- 265/40 is too tall to fit comfortably up front
- 255/40 seems like a good compromise

I wanted to go fully square with 265’s, but the M3 came with slightly taller tires at the rear, so I assume the ABS, DSC etc is calibrated for that.

[DrFerry]

Originally Posted by PKT RKT

Curious if the 255/40 + 265/40 combo will work on an E92 wearing 18x9.5 et22 APEX wheels?

- 265/35 is kinda short versus 245/40
- 265/40 is too tall to fit comfortably up front
- 255/40 seems like a good compromise

I wanted to go fully square with 265’s, but the M3 came with slightly taller tires at the rear, so I assume the ABS, DSC etc is calibrated for that.

It will work (fit) in so far as the wheel width (9.5in) and offset (et22mm) and tire sizes (255/40R18 front and 265/40R18 rear) without interference. I have run the 255/40R18 size on the OEM rear wheels (18X9.5 et23mm) mounted on the front axle myself and had no problems. However, you will slightly reduce the difference in staggered diameter versus running the stock OEM sizes (245 and 265) but not enough to trigger the ABS or DSC lights. The ABS and DSC allow for some small variations in diameter due to irregular tire wear and or inflation differences which alter the rolling radius. A more typical 'square' fitment set-up is 275/35R18 on 18X10 wheels though a 275 section will fit on a 9.5inch wide well as well. You can always check with APEX too. Hope this helps.

[PKT RKT]

Originally Posted by DrFerry

It will work (fit) in so far as the wheel width (9.5in) and offset (et22mm) and tire sizes (255/40R18 front and 265/40R18 rear) without interference. I have run the 255/40R18 size on the OEM rear wheels (18X9.5 et23mm) mounted on the front axle myself and had no problems. However, you will slightly reduce the difference in staggered diameter versus running the stock OEM sizes (245 and 265) but not enough to trigger the ABS or DSC lights. The ABS and DSC allow for some small variations in diameter due to irregular tire wear and or inflation differences which alter the rolling radius. A more typical 'square' fitment set-up is 275/35R18 on 18X10 wheels though a 275 section will fit on a 9.5inch wide well as well. You can always check with APEX too. Hope this helps.

Thank you so much.

I anticipated the slight difference in diameters - but I would think that is “preferred” over a true square setup where the front and rear tires have identical diameters…. ?

[DrFerry]

Originally Posted by PKT RKT

Thank you so much.

I anticipated the slight difference in diameters - but I would think that is "preferred" over a true square setup where the front and rear tires have identical diameters…. ?

Yes that's correct. Ideally preserving some or all of the 0.5in OEM tire size diameter split is desirable to maintain roll center height, roll-axis geometry, and weight distribution. However for reducing understeer and tire rotation needs, the 275/35R18 'square' fitment has been shown to work without triggering ABS or DSC malfunctioning. So your logic is correct. Additionally an alternative fitment is running a 255/40R18 front tire on 9.5X18 rim and a 275/40R18 rear tire on a 9.5X18 rim. This preserves the diameter staggering slightly more than 255/40R18 front with 265/40R18 rear but either will work well.

[PKT RKT]

Originally Posted by DrFerry

Yes that's correct. Ideally preserving some or all of the 0.5in OEM tire size diameter split is desirable to maintain roll center height, roll-axis geometry, and weight distribution. However for reducing understeer and tire rotation needs, the 275/35R18 'square' fitment has been shown to work without triggering ABS or DSC malfunctioning. So your logic is correct. Additionally an alternative fitment is running a 255/40R18 front tire on 9.5X18 rim and a 275/40R18 rear tire on a 9.5X18 rim. This preserves the diameter staggering slightly more than 255/40R18 front with 265/40R18 rear but either will work well.

I think I will go with the 255/40 + 265/40 combo, for now.

Slightly wider up front than stock. Should fit without an issue. Still diameter-staggered, slightly. I will probably run 18x9.5’s all around.

Thanks for the input, I appreciate it!!

[DrFerry]

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Originally Posted by PKT RKT

Thanks for the input, I appreciate it!!

There's a button for that at the bottom of each post....