Wheel Questions - United Bimmer Community

**komodo** · 04-10-2006, 08:16 PM

All right, I have a few questions on wheels. Keep in mind, these questions apply not just to BMWs, but to all car makes in general. Some of these questions may seem trivial, but I need to be sure on some things.

- Are the offset on rims the same for the front and rear of cars? For example, are there any cars that can support up to X offset on the back, but only up to Y offset on the front, or are they all the same fronts and rears?

- Bolt patterns remain constant for each car, correct? That's dictated by the car itself, and the rim must match that. For example, if you drive a certain car, every wheel you mount on that car must match that bolt pattern, right?

- How do spacers work (as detailed as possible)?

- What's the technical defination of the "ratio" of a tire?

I'll probably have more later, but that's a start. haha

Thanks guys!

**c1apton** · 04-10-2006, 08:35 PM

Bolt patterns "SHOULD" be the same, but in some cars (race stuff) that's not gospel.
Re: Offsets - there are some out there that have different offsets for brake clearance, wheel well clearance & depending on the handling prefs you want that can always be altered. IE: My bird has 15x3 on the front & the rears are 16x12 (rearend has been narrowed 38" from backing plate to backing plate and it's "tubbed") The fronts are "0" offset, rears are 9" positive offset.

I'll get you more info later (on the fly right now)

**TerryY** · 04-10-2006, 09:14 PM

My 840 has an offset of 6 mm on the front and 18 mm on the rear. This was done to "Fill" the wheel well with tire for appearance on my staggered wheels. Standard is 15 to 18 mm.

A 3 series has offsets around the 35 to 40 mm range by comparison.

Spacers are used to correct offset errors. To use 3 series wheels on an 8 you would have to use at least 20 mm spacers. That is 1 1/2" movement out on the wheels. This would be highly unstable to say the least.

Aspect ratios are explained in here: http://www.tirerack.com/tires/tirete....jsp?techid=46

**Rooz** · 04-10-2006, 09:15 PM

Is this going towards you getting new rims by any chance?

**TerryY** · 04-10-2006, 09:20 PM

All you could ever think to ask is here: http://www.tirerack.com/about/techcenter.jsp

**Numark318i** · 04-10-2006, 10:46 PM

i think he wants a write up for the site?

**komodo** · 04-10-2006, 11:02 PM

Just trying to make sure I have my information correct.

Thanks guys.