[Hyura]

So I have a G82 M4, and I’ll be first to admit that the wheel gap is pretty atrocious. That being said, my driveway had a steep incline and I scrap my front lip if I leave my drive way too fast. I’ve only back into my driveway because backing out will most definitely scrap my front lip.

As someone who never lowered their car before, I was curious if it’s possible to get tires with bigger sideways to fill in the wheel arch instead of lowering it. What are the pros and cons? What size tires would work?

[MMnut]

you want a thicker tires then you have to use smaller wheels to maintain to correct ratio. The look even worse.

[forcefed]

Leave at a 45 degree angle so you don't scratch the lip.
Otherwise the next size up is a 285/35/19 front and 295/30/20 rear, its a smidge wider and taller but nothing too wild.

[M3SQRD]

Your speedometer and DSC are programmed for a certain rolling tire diameter. If you increase the sidewall thickness, you’d typically want to run a smaller diameter wheel to maintain the same rolling diameter. For example, if you had 285/35-20 (27.9” diameter) and you switched to a 19” wheel you’d want to run a 285/40-19 (28” diameter) so the change in diameter is 1/10”. However, if you switched to a 285/40-20, you’d increase the tire diameter to 29” - 1” increase in diameter which is significant. If the delta diameters are different front to rear, you’d mess with speedometer accuracy, ABS, DSC and, if your car is AWD, you’ll likely get limp mode errors to protect the transfer case. However, some people will still increase sidewall height without changing wheel diameter primarily to increase ride comfort, not reduce the fender-tire gap.

[markoz28]

You can increase by a fraction to not throw the balance off the car, but it will not accomplish what you are looking for.

I’m currently running 285/30/20 and 295/30/20. No problems whatsoever but height only goes up about 5mm on that. Doesn’t matter to me as I’m also lowered now on HR HAS kit.

[Hyura]

Originally Posted by M3SQRD

Your speedometer and DSC are programmed for a certain rolling tire diameter. If you increase the sidewall thickness, you’d typically want to run a smaller diameter wheel to maintain the same rolling diameter. For example, if you had 285/35-20 (27.9” diameter) and you switched to a 19” wheel you’d want to run a 285/40-19 (28” diameter) so the change in diameter is 1/10”. However, if you switched to a 285/40-20, you’d increase the tire diameter to 29” - 1” increase in diameter which is significant. If the delta diameters are different front to rear, you’d mess with speedometer accuracy, ABS, DSC and, if your car is AWD, you’ll likely get limp mode errors to protect the transfer case. However, some people will still increase sidewall height without changing wheel diameter primarily to increase ride comfort, not reduce the fender-tire gap.

Since my car is an X drive model, I would theoretically get the same wheel/tire for all 4 corners if I were to increase the sidewall. Currently the fronts are 275/35/19 stock so if I were to go 275/55/19 (just making up a number) on all four corners, it should be fine for the xDrive system and slightly correct my speedometer which is currently 2mph faster then my actual speed. Is my understanding correct?

[M3SQRD]

Originally Posted by Hyura

Since my car is an X drive model, I would theoretically get the same wheel/tire for all 4 corners if I were to increase the sidewall. Currently the fronts are 275/35/19 stock so if I were to go 275/55/19 (just making up a number) on all four corners, it should be fine for the xDrive system and slightly correct my speedometer which is currently 2mph faster then my actual speed. Is my understanding correct?

A 275/35-19 tire has a diameter of 2*275*0.35/25.4+19=26.58”

A 275/55-19 tire has a diameter of 2*275*0.55/25.4+19=30.91”

Speedometer error = new diameter/old diameter = 30.91/26.58=1.163

So your speedometer would be off by 16.3%. So when your speedometer says you’re doing 60 mph, your actual speed is

Vactual = 1.163*60 = 69.78 mph

A larger diameter tire has a larger circumference and it has to travel a farther distance per revolution than your original smaller diameter tire. So your speedometer reading is slower than your actual speed. This also affects your gearing and reduces your effective final drive ratio.

[Needsdecaf]

Originally Posted by M3SQRD

A 275/35-19 tire has a diameter of 2*275*0.35/25.4+19=26.58”

A 275/55-19 tire has a diameter of 2*275*0.55/25.4+19=30.91”

Speedometer error = new diameter/old diameter = 30.91/26.58=1.163

So your speedometer would be off by 16.3%. So when your speedometer says you’re doing 60 mph, your actual speed is

Vactual = 1.163*60 = 69.78 mph

A larger diameter tire has a larger circumference and it has to travel a farther distance per revolution than your original smaller diameter tire. So your speedometer reading is slower than your actual speed. This also affects your gearing and reduces your effective final drive ratio.

This is in general true, but it's more accurate to look at manufacturer specs for overall diameter and, as quoted, revolutions per mile. Not everyone's 275/55-19 tire has the same dimensions.

Tire rack shows this pretty well on their website. I always check revs / mile when comparing tires.

[M3SQRD]

Originally Posted by Needsdecaf

This is in general true, but it's more accurate to look at manufacturer specs for overall diameter and, as quoted, revolutions per mile. Not everyone's 275/55-19 tire has the same dimensions.

Tire rack shows this pretty well on their website. I always check revs / mile when comparing tires.

Yes, that is true. Same applies to tread width, section width and weight. It was an example calculation to go along with the randomly selected tire size; however, using real numbers won’t have much of an effect on the final numbers. Furthermore, I didn’t use actual tire diameters because there are no 275/55-19 tires that match oem tire brands/performance categories.