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[OTO335i]

Hey guys,

I currently run style 193 wheels in the summer on my M-sport

wheel calculation:

Front: 8x18 ET 34 - Tire size 225/40R18
Rear: 8.5x18 ET 37- Tire size 255/35R18

For winter I run a set of style 44 wheels which has an ET of 47 and I run tires of the size 225/50R17.

I ran these last winter and they fit, the fronts come pretty close to the strut but they clear just enough, for the rears there's plenty of space and I don't like how far in the tires sit in the wheel well.

I'm trying to figure out what size of spacer I would need to bring the rear tire out to where my summer tires sit.

According to the offset calculator the rear set up of the wheels have a difference of -4MM and according to the tire size calculator the tire width difference of 27.9MM.

If my calculations are correct and I remove the 4MM from 27.9 making it 23.9MM would it be safe to assume that I can throw a 20MM spacer which would bring the tire out to be almost as close as my summer wheel would sit?

Thanks for any input guys.

[b92]

what are the widths of your style 44 wheels?

[OTO335i]

Originally Posted by b92

what are the widths of your style 44 wheels?

Originally Posted by b92

what are the widths of your style 44 wheels?

Ooopss I forgot to post that. They're 8x17

[b92]

So 0.5" difference = 12.7mm difference in rim size, or 6.35mm wider on each side of the rim. Add in the offset difference of 10mm and the total difference of the outer point sums to 16.35mm.

A 15mm spacer will do the job here, you will need longer lugs for a spacer this size

[OTO335i]

Originally Posted by b92

So 0.5" difference = 12.7mm difference in rim size, or 6.35mm wider on each side of the rim. Add in the offset difference of 10mm and the total difference of the outer point sums to 16.35mm.

A 15mm spacer will do the job here, you will need longer lugs for a spacer this size

Damn I was way off with my calculations lol because I added the difference of the tire width in there too.

Thanks for your help man!

[b92]

Originally Posted by OTO335i

Damn I was way off with my calculations lol because I added the difference of the tire width in there too.

Thanks for your help man!

Well my calculation only looked at the rim. Since you are downsizing tires, you may want to round up to the 20mm spacer.

[OTO335i]

Originally Posted by b92

Well my calculation only looked at the rim. Since you are downsizing tires, you may want to round up to the 20mm spacer.

That's what i had thought.. I'll triple check by adding my winter wheel on and measure from there.

Thanks again for your input.

[mweisdorfer]

Originally Posted by OTO335i

Hey guys,

I currently run style 193 wheels in the summer on my M-sport

wheel calculation:

Front: 8x18 ET 34 - Tire size 225/40R18
Rear: 8.5x18 ET 37- Tire size 255/35R18

For winter I run a set of style 44 wheels which has an ET of 47 and I run tires of the size 225/50R17.

I ran these last winter and they fit, the fronts come pretty close to the strut but they clear just enough, for the rears there's plenty of space and I don't like how far in the tires sit in the wheel well.

I'm trying to figure out what size of spacer I would need to bring the rear tire out to where my summer tires sit.

According to the offset calculator the rear set up of the wheels have a difference of -4MM and according to the tire size calculator the tire width difference of 27.9MM.

If my calculations are correct and I remove the 4MM from 27.9 making it 23.9MM would it be safe to assume that I can throw a 20MM spacer which would bring the tire out to be almost as close as my summer wheel would sit?

Thanks for any input guys.

I'd go 225/45/18 square for winter tires

Or perhaps

225/40/18

[OTO335i]

Originally Posted by mweisdorfer

I'd go 225/45/18 square for winter tires

Or perhaps

225/40/18

It's better to run a thicker sidewall in winter so that you can dig into the snow. This is why I went to a 17 inch wheel for my winter set up. I wanted the thickest sidewall I could throw on my car and I think a 50 series is as thick as I can go, wish I could throw a 60 series on there lol

[mweisdorfer]

Originally Posted by OTO335i

It's better to run a thicker sidewall in winter so that you can dig into the snow. This is why I went to a 17 inch wheel for my winter set up. I wanted the thickest sidewall I could throw on my car and I think a 50 series is as thick as I can go, wish I could throw a 60 series on there lol

I won't debate what you are saying isn't true etc. BMW engineers determined that 225/45/17 was sufficient.

If anything go with less width.

I really think unless you are in a state like Maine, Vermont, Minnesota or the UP Michigan, a size of 225/46/17 will be just fine.

I do respect you maximizing functionality of your car in the winter.

[OTO335i]

Originally Posted by mweisdorfer

I won't debate what you are saying isn't true etc. BMW engineers determined that 225/45/17 was sufficient.

If anything go with less width.

I really think unless you are in a state like Maine, Vermont, Minnesota or the UP Michigan, a size of 225/46/17 will be just fine.

I do respect you maximizing functionality of your car in the winter.

Yeah I get what you mean but even if an engineer gives his opinion doesn't mean that it works for everyone, I find that someone's opinion reaches a certain limit even though their experts. "it's still just that person's opinion with what they have at hand"

Yes I dropped down to a 225 for less width and went with 50 so that it can maximize the functionality like you mention. Also, I have the m-sport model so I like to bring it as high off the ground as I can, we do get quite a lot of snow up here in Ontario at times lol and the last thing I want to do is plow the street with my bumper lol