Front wheel spacer / steering feel question..

[TurnAround]

3.0i, with 18" wheels. Like all 18's, and all 19" fronts, they are 48ET. I've never understood the exact use of the BMW ET #, but I do know that it describes the distance from the wheel's hub facing, to the outside edge of the rim. The rear wheels from a staggered set of BMW 19's or 20's have an ET of 45. Because the E53 X5 has hub flanges that stick out to the same point on the front as the rear, this means the wheel's outside rim edge will push out 3mm more.

I also know that when one buys wider BMW wheels, ALL of the extra width goes to the inside of the wheel. The car gets fatter.. underneath. They do not push out to the outside more. The ET numbers remain the same.

I'm about to go from 18"x8.5 all around, to Style 132 19"x9" all around. The ET is still 48. The extra half inch will pooch to the inside of the car. I'm adding 30mm wheel spacers to the back for sure (for looks). The question is, should I add wheel spacers to the front (again, this is for looks), and if so, how many mm?

Wait.. there's one more factor to consider; Wheel spacers push the wheel facing out, which means the push the steering axis point out too. The farther out the wheel's center line is from the steering axis, the more "dead" it will feel in steering.

I'm thinking about going with 10mm spacers in the front and that the steering axis to wheel center line point won't be effected, because my new wheels will be 1/2" wider to the inside. 12.5mm is one half inch.

What's your opinion on looks; No front spacer? 10mm front? Other? (Rember the rear's will have 30mm spacers, with ET48 wheels)

Opinions on the steering analysis?

Thanks guys.

[Eurosport]

http://www.1010tires.com/WheelOffsetCalculator.asp

[Arudge]

Spacers should be fine, make sure they are hub and wheel centric, especially in the front.

[TowX]

Originally Posted by TurnAround

I'm about to go from 18"x8.5 all around, to Style 132 19"x9" all around. The ET is still 48. The extra half inch will pooch to the inside of the car.

Thanks guys.

Not quite true. Although the wheel will be 1/2" wider, by maintaining the same et48 some of the 1/2" will be inside and some outside. By doing the math, the extra 1/2" (roughly 12.7mm) would give you about 6.3mm more outside and 6.3mm more inside. Thus by maintaining the same offset, the width is evenly split around the center and should maintain the steering feel and bearing loads.

I have used spacers for years in many cars (Audi, Porsche, BMW) and have no problem with their use. The caveat is that only good hub-centric spacers are used (H&R for example). But the front of BMW's with the steering and suspension geometry is very sensitive to drastic offset changes. I run 10mm rear spacers on the X5 and might try 15's with the winter setut, but I won't add front spacers. I tried spacers on my 528 and while it looked better, the front end just never felt right so I went back to no spacers at all.

[TurnAround]

Originally Posted by TowX

Thus by maintaining the same offset, the width is evenly split around the center and should maintain the steering feel and bearing loads.

I run 10mm rear spacers on the X5 and might try 15's with the winter setut, but I won't add front spacers. I tried spacers on my 528 and while it looked better, the front end just never felt right so I went back to no spacers at all.

Are you sure about the extra width being split in two? My old 17" wheels were really narrow and they didn't stick way in. On the outside, they look just like the 18's do now. However, what you are saying makes perfect sense. It would be smart to spllit the diff so that the steering remained "factory".

So what you are saying is that I should just get the new wheels and do nothing with the fronts because they'll stick out just a little further, and that for the rear I should switch to buying 25mm spacers instead of 30mm.. eh??

[TowX]

Yes I'm sure about the extra width of the wheels. I pulled out my calculator and did the math to get those numbers.

My rule of thumb has always been to try without the spacers first to see what you have. My winter wheels are virtually identical to what you're thinking about getting- only 18's. But 9" wide with et45 offset. The fronts could stand to go out a bit but I'm happy as it is. The rears could go way out. I've got 10mm spacers back there and could easily go to 25. My mistake was just not getting the same wheel in an et20 for the rear since it was offered as both a 20 and 45mm offset. But at least this way I can rotate the tires.

So I'd suggest getting the wheels and use either the 25 or 30mm spacer for the rear (Can't tell you if the 30 will work sorry). Mount up the wheels, then decide if you need the extra 10mm spacer for the front. My guess is no, but that's your choice based on how it fits.

And don't forget the longer bolts to go with the wider spacers.

[TurnAround]

Originally Posted by TowX

And don't forget the longer bolts to go with the wider spacers.

Cool. This was exactly the feedback I needed. I'll order the rear spacers only and wait on the fronts. I agree that 5mm should be avoided on the fronts because you don't get hubcentric. Gotta go 10mm to start getting that.

On the rears, I'll get the H&R DRA kit. In either 25mm or 30mm this kit bolts to the car's hub flange with included silver bolts, then you bolt the wheel to the spacer with the car's stock bolts. You pick up another quarter pound of weight from the extra bolt heads and the steel thread inserts, but it is a veeeery solid setup. Plus the added weight is at the center of the wheel.

Yeah.. 25mm or 30mm. Torture decision. I've determined that 30mm is not too much. The problem is that if you go 30mm and no front, you're introducing a tad more understeer. I replaced the suspension on the Coupe and drastically reduced understeer (and actually have oversteer now). But I'm sticking with stock suspension on the X so I don't want to induce much of a change. But If I do get front spacers after all, I'll probly wish I'd gone with 30mm in the rear and not 25mm HA!

Thanks for the advice.

[paulymano]

Hi,
Did you end up going with 25mm or 30mm? How do they look? I'm looking to get spacer for my 4.6is. I'm only interested on getting them on the rear wheels. Right now, I can't decide to get the 20mm, 25mm or the 30mm. I think the 30mm might be too much. I'm thinking more for the 25mm. Any suggestion/advice would be appreciated.

thanks

[TurnAround]

Originally Posted by paulymano

Hi,
Did you end up going with 25mm or 30mm? How do they look? I'm looking to get spacer for my 4.6is. I'm only interested on getting them on the rear wheels. Right now, I can't decide to get the 20mm, 25mm or the 30mm. I think the 30mm might be too much. I'm thinking more for the 25mm. Any suggestion/advice would be appreciated.

thanks

I went with 25mm. 30mm would have been "perfect", but I should point out that I have a 3.0i and non staggered wheels. Your 4.6is may have a different hub flange offset (distance out). I know your wheels will be out about 3mm more. Someone else here with a 4.6 or 4.8 should confirm the wheel spacing and ET numbers for you, but I believe that 30mm would not be too much for your setup. Can't go wrong with 25mm either.

If you go with 20mm you won't be able to get the kit that bolts on to the hub first and then reuses the wheel bolts (highly desirable). Only the 25mm and 30mm kit has this feature. Read through the thread for part numbers. I'd go with at least the 25mm.

[X5rolls]

What is the final word on front wheel spacers? I like the way the rear spacers look but am hesitant till I find someone who likes them in the front? Thanks