The HOOF

OK, new guy and need some help here. This has been asked somewhat, however I haven't really found a diffinitive answer. In fact the more I read the more I'm not sure there is one.

I have a 535xi 18 stock staggered setup now and want to do staggered 19s. I have read the xi wheels and susp thread to death.
Not to mention many other threads and charts as well.

I don't want to drop (upstated NY). One of the fellows here mentioned to me I could go +5 on the side walls and I would be good without having to drop her and fill up the wheel wells a little. Ultimately adding an 1" to the Dia of the setup.

So 245/40/19 f and 275/35/19 r rather than the reccommended set up of 35 and 30. I don't see to many folks doing this so it makes me nervous.

I called on tires and they didn't like the idea to much. Even here it seems that some folks say it will be fine and others
mention the rolling dia and potential issues caused to the awd and other things.

My question: can I do this with out issues or not? I understand there may be two rules of thought but would prefer to
come to the experts and get your opinions.

Thanks

TLO03

i have not done the math on your suggested setup, but as long as the wheels front to back are with in 3% rolling diameter i would not worry

e60oholic

Tire places are so weird. When i was looking for tires i talked to Dunn and they refused to mount non run flat tires on my car seeing it came with run flats.

e60oholic

delete

luigi524td

This tire size comparison calculator will help you determine the information: http://tinyurl.com/2yc8h

In general, increasing the rolling radius (and overall change in diameter) will impact the accuracy of your speedometer. That said, as long as the front to rear wheel rolling radius remains constant the drive train and electronics won't think something is odd and start trying to correct what may be read as tires slipping. This is especially the case for all-wheel drive systems where the electronics will start manipulating the front to rear power based on invalid data.

So, as previously stated, it's best to stick close to the original overall wheel/tire diameter +/- 3% so, smaller diameter wheels permit higher aspect tires - larger diameter wheels fit lower aspect tires (17" wheels & 50 series tires vs 20" wheels and 35 series tires) .

The HOOF

So based on the tire calc you provided (Thank you) then:

Tire Size Comparison
Specification Sidewall Radius Diameter Circumference Revs/Mile Difference
245/40-18 3.9in 12.9in 25.7in 80.8in 784 0.0%
245/40-19 3.9in 13.4in 26.7in 83.9in 755 3.9%
Specification Sidewall Radius Diameter Circumference Revs/Mile Difference
275/35-18 3.8in 12.8in 25.6in 80.4in 788 0.0%
275/35-19 3.8in 13.3in 26.6in 83.5in 759 3.9%

Almost 4% so not so good. With the staggered 19s being wider by 1/2 (8.5 and 9.5 ) does that give me any play or already included

cryptical

What's more important are the ratios and differences between the 19" wheels from one another, that's a 3.9% from the 18's to 19's, so that's not accurate. If the 245/40/19's are within 3% of the 275/35/19's, then you're fine. But like others stated, this can still throw off your speedometer and odometer readings because of the overall diameter difference between the 18's and 19's.

The HOOF

Alright now I get it. I can't believe it took this long but I'm with you now. Thanks.
So that being said:

Specification Sidewall Radius Diameter Circumference Revs/Mile Difference
245/40-19 3.9in 13.4in 26.7in 83.9in 755 0.0%
275/35-19 3.8in 13.3in 26.6in 83.5in 759 -0.5%

I'm golden. Others have done this I just couldn't wrap my head around it.

What did you do to yours? drop or not. Tires?

cryptical

Just tires/wheels...next step is to drop with coilovers. I went with 19" staggered, but 245/35 and 275/30.

stearnsn

What are you going to do with your 18's?