[m235red]

What wheel specifications for an M240i xdrive are best suited for drag racing?
I've always had a rear-wheel drive car, and now I'm a little confused about the wheel measurements because it's all-wheel drive.
I'm building a car to run in the 6s in 201m

[dradernh]

Originally Posted by m235red

What wheel specifications for an M240i xdrive are best suited for drag racing?
I've always had a rear-wheel drive car, and now I'm a little confused about the wheel measurements because it's all-wheel drive.
I'm building a car to run in the 6s in 201m

I know little about drag racing, but forum member XutvJet is most likely the person who can best advise you here.

I went to https://robrobinette.com/et.htm to see how much RWHP would be required to run under 7s. Depending upon how much weight you end up running (I plugged-in values from 3900 to 4050), a 7s 1/4-mile ET required well over 2,000 RWHP. Consequently, I'm not sure I understand the problem.

[m235red]

Brother, what I'm looking for are wheel and tire measurements that can be used on a car like this xdrive, if I use the wrong measurements they could harm the differential or not?

[Kernel Kurtz]

Originally Posted by m235red

Brother, what I'm looking for are wheel and tire measurements that can be used on a car like this xdrive, if I use the wrong measurements they could harm the differential or not?

Fit the widest tires you can in the front and back. Probably 245-255 in the front and 275-285 in the back. Keep the rolling diameters within 1-1.2%. You may find more info on specifics like wheel widths and offsets in the wheels and tires subthread. Have fun and do share some time slips in the future.

[XutvJet]

As Kernel Kurtz noted, you need to keep the rolling diameter between the front and rear axles within about 1% or less.

Given that your car is AWD with a RWD bias, there's really no need for a fat, full on slick. You can cram a 26 inch tall slick in the back, but you'll struggle to find 16" wheels that will clear the brakes. If it were me, I'd just run a set of 17" drag radials at all four corners.

As you probably know, you'll need around 530-550whp to run upper 6s in the 1/8 mile and around 650-680whp to run lower 6s. The N55 can make 500-600whp, but you're really walking on egg shells. These motors, while stout, just weren't designed for these levels of power, especially all the ancillary systems. Same goes for the transmission. It won't live long if you're racing it often. Maybe a season or two. Same goes for the transfer case, rear diff, and axles. Big torque and hard launches break things.

I wish you the best, but I hope you've got deep pockets and can do transmission and motor work because you're going to break a lot of stuff. Also, you'll endlessly be troubleshooting tuning, boost, limiter issues, etc. with the motor when pushing those levels of power. Many will say just get an M240 with the B58, but I promise you, it will be no different other than the fact that the short block is stronger. It's everything else around that block that gets taxed heavily running huge power. If BMW thought the N55 and B58 could handle big power, they would have never developed the S-line M motors.

What's the reason why for wanting to run 6s in the 1/8 mile, specifically? Bragging rights? There are a lot of better cars out there where it's far easier and cheaper to run 6s in the 1/8 mile. Upper 6s equates to around 10.6-10.7 in the 1/4 mile and lower 6s in the upper 9s.