machining wheel to change offset, possible?

[jszy25]

Hopefully the pro's can answer this question for me....

Can the mounting surface of a wheel be machined down to change the offset of a wheel? For example....if I wanted to put BMW Style 5's et-20 (like hooj had) on my 99 M3, but I want to run wider tires then he did (215-40-17), could a machine shop mill off some material to change the offset? Is this possible? Would it degrade the strength of the wheel?

I dont even know how much would need to be taken off, I just want to find out if this is possible because I couldn't find any information on the subject.

[NY550i]

It depends how much space there is to shave.

Shaving wheels will make the offset go up... on the Style 5s you can probably shave only a couple MMs and its not enough to fit on the 99 M3.

[Daved]

It's possible, I know some (or most) machine shops in the US won't want to do it because of the risks but it's commonly done here.

[jszy25]

It depends how much space there is to shave.

Shaving wheels will make the offset go up... on the Style 5s you can probably shave only a couple MMs and its not enough to fit on the 99 M3.


Well making the offset go up is what I would need to make them fit. I would also have rolled fenders for extra space.

Shaving a only a couple mm's is probably not enough, like you said. I dont know how to convert an offset # into a measurement like mm's, so I dont exactly know how much material would need to be shaved off. Probably to the point where the integrity of the wheel would be lowered (which I was afraid of), but maybe not.

[kosta]

hre did mine but it was only 3mm
hardly worth it

[Daved]

The offset number is in milimeters.

http://www.tirerack.com/wheels/tech/techpage.jsp?techid=101

[jszy25]

The offset number is in milimeters.

http://www.tirerack.com/wheels/tech/techpage.jsp?techid=101

I didnt know that, thanks for clearing that up. So im going to assume that shaving off 5mm is a lot, maybe too much....and that would not even make a big enough difference for what im looking to do. that sucks haha

[NY550i]

Well making the offset go up is what I would need to make them fit. I would also have rolled fenders for extra space.

Shaving a only a couple mm's is probably not enough, like you said. I dont know how to convert an offset # into a measurement like mm's, so I dont exactly know how much material would need to be shaved off. Probably to the point where the integrity of the wheel would be lowered (which I was afraid of), but maybe not.

If you have ET20 right now and you shave 3mm you will have ET23.

I noticed you are in NY... if you want come by Queens NY (near JFK airport) i'll have my CNC machinist look at the wheels and see how much he can shave off
We usually charge $40 per wheel to shave offset but i'll do it for $25.

[jszy25]

If you have ET20 right now and you shave 3mm you will have ET23.

I noticed you are in NY... if you want come by Queens NY (near JFK airport) i'll have my CNC machinist look at the wheels and see how much he can shave off
We usually charge $40 per wheel to shave offset but i'll do it for $25.
I dont have the wheels yet, I am trying to find out if they will actually fit first. Thank you for the offer though and if I do get the wheels I will definitly contact you about having your machinist look at them.

Unfortunately my offset is much higher then that, so I dont think enough can be taken off before it becomes unsafe.

[jszy25]

I've thought more about this and I realized that these wheels are made for a car that is 3700+ lbs. My car is a little over 3100lbs. This makes me believe that shaving off 5 or more millimeters from the mounting surface to change the offset would not degrade the strength of the wheel enough for a car that is several hundred lbs. lighter.......does anyone have anything to say about this?

[NY550i]

I've thought more about this and I realized that these wheels are made for a car that is 3700+ lbs. My car is a little over 3100lbs. This makes me believe that shaving off 5 or more millimeters from the mounting surface to change the offset would not degrade the strength of the wheel enough for a car that is several hundred lbs. lighter.......does anyone have anything to say about this?

It has nothing to do with how much the vehicle weighs.
It matters how much backspacing the rim have to shave.

Some rims you can only shave couple of millimeters before your literally mounting the back of the face of the wheel on the hub of your car and that is very unsafe... you really do not want the wheel to snap off the lug bolts while your doing 60+ mph.

[gerry_miranda]

Safety First

[TheBlueB]

I know that 1"=25.4 mm and this posting is very informative!
I have two set of E34 rims but I have a E36 and I did not think that we can shave offset. wow.. I am learning a lot from this forum.
Thanks guys! I need to find someone to shave off my offset now then. :D