I just can't get my head around wheel fitments
 

Wheel matching is one of my kryptonites. I struggle getting my head around offset vs width and separately tires sizing and ultimately what will work togehter.

I'm starting to shop for a set of wheels / tires for the x3. It currently is on BMW style 279 wheels.

Basically, I'm trying to figure out if I can use 1er, e46 and/or e90 wheels on this thing.

They're 8*17 all around ET46 with a 72.5mm bore and a 5*120 bolt pattern.

Questions:
1. offset - how much flexibility do I have before I need a spacer? Is it better to go with a wheel with a higher value offset or smaller?

2. How do offset and width interact? IE: If I go to a 7.5" or 8.5" wheel, what do i need to do to the offset #

2. Didn't e46 x-drive cars have different offset compared to RWD cars? Did e90 cars have the same offset, or are they different too?


I found this chart and am trying to figure out what wheels I can use on this thing.

1 Series E81/82/87/88 = PCD 5x120, centre bore 72.5mm and M12x1.5 bolt thread. ET 35-45

3 Series E21 = PCD 4x100, centre bore 57.1mm and M12x1.5 bolt thread. ET 12-20

3 Series E30 = PCD 4x100, centre bore 57.1mm and M12x1.5 bolt thread. ET 15-35
3 Series E30 M3 = PCD 5x120, centre bore 72.5mm and M12x1.5 bolt thread. ET 27-30

3 Series E36 = PCD 5x120, centre bore 72.5mm and M12x1.5 bolt thread. ET 30-47
3 Series E36 M3 = PCD 5x120, centre bore 72.5mm and M12x1.5 bolt thread. ET 35-47

3 Series E46 = PCD 5x120, centre bore 72.5mm and M12x1.5 bolt thread. ET 30-47
3 Series E46 M3 = PCD 5x120 centre bore 72.5mm and M12x1.5 bolt thread. Fronts ET 30-47, Rears ET 20-27,

3 Series E90/91/92/93 = PCD 5x120, Centre bore 72.5mm and M12x1.5 bolt thread. ET 30-45
3 Series E90/92/93 M3 = PCD 5x120, Centre bore 72.5mm and M12x1.5 bolt thread. ET 34-37

5 Series E28 = PCD 5x120, centre bore 72.5mm and M12x1.5 bolt thread. ET 18-25

5 Series E34 = PCD 5x120, centre bore 72.5mm and M12x1.5 bolt thread. ET 13-20
5 Series E34 M5 = PCD 5x120, centre bore 72.5mm and M12x1.5 bolt thread.

5 Series E39 = PCD 5x120, centre bore 74.0mm and M12x1.5 bolt thread. ET 15-25
5 Series E39 M5 = PCD 5x120, centre bore 72.5.0mm and M12x1.5 bolt thread. ET 15-25

5 Series E60/61 = PCD 5x120 centre bore 72.5mm and M12x1.5 bolt thread. ET 15-32
5 Series E60 M5 (Saloon) = PCD 5x120, centre bore 72.5mm and M12x1.5 bolt thread. ET 12-32
5 Series E61 M5 (Touring) = PCD 5x120, centre bore 72.5mm and M12x1.5 bolt thread. ET 12-32

6 Series E24 = PCD 5x120, centre bore 72.5mm and M12x1.5 bolt thread.

6 Series E63/64 = PCD 5x120, centre bore 72.5mm and M12x1.5 bolt thread. ET 14-20
6 Series E63/64 M6 = PCD 5x120, centre bore 72.5mm and M12x1.5 bolt thread. ET 12-20

7 Series E32 = PCD 5x120, centre bore 72.5mm and M12x1.5 bolt thread. ET 19-26

7 Series E38 = PCD 5x120, centre bore 72.5mm and M12x1.5 bolt thread. ET 13-25

7 Series E65/66/67/68 = PCD 5x120, centre bore 72.5mm and M14x1.5 bolt thread. ET 15-25

8 Series E31 = PCD 5x120, centre bore 72.5mm and M12x1.5 bolt thread.

X3 E83 = PCD 5x120, centre bore 72.5mm and M14x1.5 bolt thread. ET 40-45

X5 E53 = PCD 5x120, centre bore 72.5mm and M14x1.5 bolt thread. ET 40-45

X5 E70 = PCD 5x120, centre bore 74.0mm and M14x1.25 bolt thread. ET 37-53

X6 E71 = PCD 5x120, centre bore FRONT 74.0mm, centre bore REAR 72.5mm and M14x1.5 bolt thread.

Z1 E30Z = PCD 4x100, centre bore 57.1mm and M12x1.5 bolt thread.

Z3 E36 = PCD 5x120, centre bore 72.5mm and M12x1.5 bolt thread. ET 30-40

Z3 M Coupe/M Roadster = PCD 5x120, centre bore 72.5mm and M12x1.5 bolt thread.

Z4 E85 = PCD 5x120, centre bore 72.5mm and M12x1.5 bolt thread. ET 45-52

Z8 E52 = PCD 5x120, centre bore 72.5mm and M12x1.5 bolt thread.
yura

Higher offset wheels go further into the wheel well / towards the strut.

Generally speaking, modern cars have tons of fitment tolerance because they are shipped with gigantic and wide wheels.

There were no wheel fitment differences with E46 xdrive vehicles. BMW shipped standard wheels on them. I can't speak to E90 RWD vs. xDrive, but the default offsets were different.

As a general rule, cosmetically, you will want a slightly smaller offset vs. a slightly larger offset. Larger offsets mean further back in the wheel well, which generally looks pretty funny.

I will say that on an X3 or similar type vehicle, aftermarket wheels look pretty silly. I would personally stick to one of the stock sets of wheels.

Best advice ever !!

I went through getting different wheels back on my E46 330i and it was a nightmare, I must have purchased at least 5 sets of wheels and ended up just keeping the stock ones. Trying to get the right fit was super tough but also one other MAJOR factor you don’t have in your equation is wheel weight.
I remember putting on the hottest looking wheels on my E46 but the car became a slug and felt like it was being dragged down and the reason was because the wheels were so damn heavy.

I now only stick with stock wheels for a spare set for my cars.

BMW wheels are usually at the heavy end of what's available. I can generally save 5-10lbs. per wheel aftermarket. :dunno:

That is good you are finding lighter weight wheels, where were you back in 2003 when I was going crazy trying to find hot rims for my car ... lol now that I think about it you were probably in junior high school :D

I'm (slightly) older than that. :p

There are plenty of wheel fitment calculators out there, or you can just create one in a spreadsheet program.

At the very least, it helps to get some basic data on the car in question as fitted with the factory wheels and tires (or whatever you have on the car that currently fits):

1) How much clearance from the strut to the tire?
2) How much clearance from the tire to the inner edge of the fender?

"Offset" is just a measurement of the hub face of the wheel relative to the centreline of the wheel. A +46mm (the + is implied) offset wheel has the hub face 46mm outboard of the center of the wheel. That means for an 8" (203.2mm) width wheel, 147.6mm of the wheel is inboard of the hub and 55.6mm is outboard.

If you wanted to go to a wider wheel (let's say 8.5" for discussion purposes) but maintain your existing tire-to-strut clearance, just work the equation in reverse.

You want 147.6mm of wheel inboard of the hub (same as before) but now you've added 0.5" (12.7mm) of width, which has to be outboard of the hub (closer to the fender). So your outboard measurement goes from 55.6mm to 68.3mm. Therefore your offset wants to be 39.7 (call it 40mm).

You can make offset adjustments using spacers but recall that you can only make a positive offset smaller, not larger. A 10mm spacer on a 46mm offset wheel changes the effective offset to 36mm.

Thanks for this. Is there an disadvantage to having moreof the wheel outboard (ie the same width with a smaller offset) other than having part of the wheel outside of the fender throwing rocks out?

There are tradeoffs to various fitment compromises, and you're always compromising something.

Any change in offset affects the scrub radius of the suspension, and scrub radius has a large effect on steering feel and tramlining. For a small change like 1/2", you might not notice it. On my ZHP I went from an 8" front wheel to a 9" wheel and I really noticed the tramlining get much worse. Having said that, the E90 and later front suspension vastly improves this because of the virtual instant center caused by the double outer balljoint configuration.

Generally you move to a wider wheel for increased grip, or improved looks (as Nick noted, cars look dumb when the wheel and tire package is inboard of the fender by a large amount). But as you noted, when you move the wheel out you will cause debris to get thrown into the trailing edge of the fender. :dunno:

I remember having a lot of trouble figuring out fitments for my e70 x5 diesel. Was it MY2011? Weird stuff like X5 & X6 hubs are not the same or front/rear differences. Ahh, so happy not to have to deal with that thing. Also those wheels were a back breaking 70 to 80lbs each with tires.