RC090 Style 5 Wheels Question

[shortair44]

Hi everyone, I am new here. I am trying to identify what type of wheels I have on my 2004 BMW M3. I know they are BBS RC090 and say 8Jx17H2 lS20 and 1 093 531. I also know the hub bore is 74.1mm. What I don't understand is why/how they have 225/45/18 on the front and 255/40/18 on the rear? Also, all of the valve stems are on the inside of the wheel (super annoying). Are they 17in wheels or 18in wheels? I am so confused. Any help would be greatly appreciated.

















UPDATE: I just measured them and the diameter measures 18in. Does that mean they are stepped to 18in (since the logo shows 8Jx17H2)? I also tried measure the width (which is hard with the tire on) and it seems like 8 - 8.5 in. I also tried measuring the offset through the backspace (5.75in) and I got 32mm offset. Has anyone ever heard of an RC090 18in in 32mm offset?

[MarcoZandrini]

The wheels are 18” wheels because 18” tires are mounted on them. The reason the front tires are narrower than the rear (known as “staggered”) is to a) prevent oversteer, b) the engine’s power requires more rubber, and c) it looks cool.

I’m not a wheel expert but I bet those wheels aren’t the best quality. Snap a picture of one of the wheels, upload the picture to a photo sharing website and then post the link.

[shortair44]

The wheels are 18” wheels because 18” tires are mounted on them. The reason the front tires are narrower than the rear (known as “staggered”) is to a) prevent oversteer, b) the engine’s power requires more rubber, and c) it looks cool.

I’m not a wheel expert but I bet those wheels aren’t the best quality. Snap a picture of one of the wheels, upload the picture to a photo sharing website and then post the link.

I am pretty sure these were custom made by the previous owner. I found a 17in to 18in step kit from Blackforest Industries and that was like $530 per wheel. They are in great shape but I'm thinking of upgrading to a different set of wheels so I think I am going to sell them or trade them. I was curious what these would be worth. Normal style 5 pricing or more since they are custom 18in. A few others suggested around $1500+ with tires since they are 18in.

Here is a link to the Blackforest Industries kit: https://blackforestindustries.com/pr...onversion-kit#