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Discussion Starter · #1 ·
I currently have OEM 16” tires/rims on my 2005 BMW 325CI.

Looking to upgrade to 18” if possible. I found 18” Msport Rims which previously came off an F30. Tire size 235/45/18 in the front and 255/40/18 in the rear.

Would these be a good fit?

If not, what else would you guys recommend?

Any advice would be great.
 

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I think those tires will be oversized, and your car might not like them. Your E46 likes a 225/40x18, this gives a tire that's roughly 25 inches in diameter, the 235/45x18 gives a diameter of almost 26.5, this diameter difference will affect the gear ratios and this might give you a performance curve that reminds you of a snail or slug. Your rear tire option should be a 255/35, not 255/40. Your front should be a 235/40, but this entirely ignores the whole issue of offset that can make your wheels put the tires into the fenders.


225 (width) x .40 (aspect ratio) gives one sidewall in millimetres (90 mm), double it to 180, then divide by 25.4 to convert to inches, then add the rim diameter (18) to get the overall diameter. You need the final result to be roughly 25 inches. 225/40x18 = 25.08 inches. 255/40x18 = 26.03 inches, whereas the 255/35x18 = 25.02 inches. You can play with the numbers to see how much too big or too small the tires will be. This calculation only gives the diameter, but the first number, 225, 235, 255, etc., gives the width. Your factory wheels have an offset (ET) of 41, the F30 gets an offset of 34 and 47. 37 should be okay on the front, if you have trouble, it should be in the rear because the offset might hit the suspension, but you can cure this with a spacer. If you need spacers, be sure to ask about longer lug bolts.

 

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Discussion Starter · #4 ·
I think those tires will be oversized, and your car might not like them. Your E46 likes a 225/40x18, this gives a tire that's roughly 25 inches in diameter, the 235/45x18 gives a diameter of almost 26.5, this diameter difference will affect the gear ratios and this might give you a performance curve that reminds you of a snail or slug. Your rear tire option should be a 255/35, not 255/40. Your front should be a 235/40, but this entirely ignores the whole issue of offset that can make your wheels put the tires into the fenders.
Very helpful. So I should instead look for tires/rims for 235/40 front, 255/35 rear. What about the size? Would 18” be too big for the housing? Should I instead look at 17”, or does that not matter?

These were the tires I was trying to get. I think they’re style 400?

Is there something specific that I should be looking for instead? Really appreciate it.

917943
 

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Very helpful. So I should instead look for tires/rims for 235/40 front, 255/35 rear. What about the size? Would 18” be too big for the housing? Should I instead look at 17”, or does that not matter?

These were the tires I was trying to get. I think they’re style 400?

Is there something specific that I should be looking for instead? Really appreciate it.

View attachment 917943
18" fit perfectly, you can do 235/40r18 and 255/35r18 or 225/40and 255/35 both fit perfectly
 

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18s will look good, but the F30 uses a different offset, and this might be a challenge. I think you posted a Style 397, which should be a square fitment (all 4 tires the same size). A 235/40 will fit good and look nice.
 

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Offset from an F30, if those are 397s offsets are 34 and 47. An 18x8 ET34 wheel isn't super aggressive and will fit fine, and an 18x8.5 ET47 is hardly a change from stock, so no issues there.
 

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Discussion Starter · #8 ·
18s will look good, but the F30 uses a different offset, and this might be a challenge. I think you posted a Style 397, which should be a square fitment (all 4 tires the same size). A 235/40 will fit good and look nice.
Amazing. Thank you for all of the advice and the effort you put into these responses.

Now the search continues. Although not sure a decently priced set that’s in good shape would be attainable via Craigslist of Facebook Marketplace, eBay. Might need to use ECS or something similar to find such specific products. Anywhere else you might recommend?
 

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I loved my 16" tires...with monster tires...stock size...I forget. I could fill those up with helium and ford rivers and fjords.

Also, your tires are your final drive gear, so overall, the smaller diameter and weight closer to the axle gives you more torque. I think you might notice the difference with a larger tire, greater weight.

But...where do you live? Do you get snow, have potholes? Might want to make sure you have room to get a hose in to rinse off your wheel wells.

I went a while with my oe 16s, but they were a nightmare to clean. Think of simple design if you like your wheels clean...I had too much going on. Those pictured above are the ones I have now (square)...very easy to clean. :)
 

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18s will look good, but the F30 uses a different offset, and this might be a challenge. I think you posted a Style 397, which should be a square fitment (all 4 tires the same size). A 235/40 will fit good and look nice.
Those are 400s...or at least look like my 400s.
 

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Discussion Starter · #12 ·
I loved my 16" tires...with monster tires...stock size...I forget. I could fill those up with helium and ford rivers and fjords.

Also, your tires are your final drive gear, so overall, the smaller diameter and weight closer to the axle gives you more torque. I think you might notice the difference with a larger tire, greater weight.

But...where do you live? Do you get snow, have potholes? Might want to make sure you have room to get a hose in to rinse off your wheel wells.

I went a while with my oe 16s, but they were a nightmare to clean. Think of simple design if you like your wheels clean...I had too much going on. Those pictured above are the ones I have now (square)...very easy to clean. :)
Thanks for the color here. I live in Los Angeles. The car has never seen snow... nor do I think it ever will. So it seems that I shouldn't move forward with the tires that I shared here. Back to the drawing board and the search continues.
 

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Discussion Starter · #13 ·
Offset from an F30, if those are 397s offsets are 34 and 47. An 18x8 ET34 wheel isn't super aggressive and will fit fine, and an 18x8.5 ET47 is hardly a change from stock, so no issues there.
Interesting. So you think that these will fit fine? Your response goes against what everyone else has said here...

Now I'm confused.
 

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The issue is not the widths of the wheels or even the offsets. The tires are likely too big to fit properly in the smaller wheel wells of the E46. You can always replace the tires if you really like the wheels.
 

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I would use the ZHP figures as a guide. We know those fit. Going bigger on tires, and less on offset may cause interference with body, and other problems, as pointed out. I would want to get any used rims checked for runout before laying out big cash. Tire Rack has data on diameters, etc.
17" will give better ride, cost less, last longer, all things being equal.
 

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Interesting. So you think that these will fit fine? Your response goes against what everyone else has said here...

Now I'm confused.
The wheels themselves are fine, the tires on them are too tall. You would want to stick with a 225/40 or 235/40r18 front and 255/35r18
 

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Brian,

Pause a second here. You have 5 posts and are looking for tire advice, but you want 18" rims so it's actually rim and tire advice. Nobody should give tire/rim advice until they ask you questions. So, here's mine: what are you trying to achieve here with new tires and new rims? If it's a style, and looks and as wide a tire as you can stuff under the fenders and you don't care how badly the car handles, or vibrates or steers on pavement imperfections - please ask that question so that we know you only care about cosmetics because that's a main theme with putting bigger stuff on.

It sounds like you are getting an education in an extremely important measurement called "offset" which was designed into your car such that if you put rims on with a different offset you will not have the factory handling, braking, pavement response it came from the factory with. Stray to a different offset and you may be proud of how it looks stopped in your driveway but it may drive and handle like a Nissan Sentra with worn suspension.

Anyhow - no point in tire/rim advice until we know what you want to achieve with new tires/rims.
 
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Discussion Starter · #18 ·
Brian,

Pause a second here. You have 5 posts and are looking for tire advice, but you want 18" rims so it's actually rim and tire advice. Nobody should give tire/rim advice until they ask you questions. So, here's mine: what are you trying to achieve here with new tires and new rims? If it's a style, and looks and as wide a tire as you can stuff under the fenders and you don't care how badly the car handles, or vibrates or steers on pavement imperfections - please ask that question so that we know you only care about cosmetics because that's a main theme with putting bigger stuff on.

It sounds like you are getting an education in an extremely important measurement called "offset" which was designed into your car such that if you put rims on with a different offset you will not have the factory handling, braking, pavement response it came from the factory with. Stray to a different offset and you may be proud of how it looks stopped in your driveway but it may drive and handle like a Nissan Sentra with worn suspension.

Anyhow - no point in tire/rim advice until we know what you want to achieve with new tires/rims.
Thank you for chiming in. I don’t like the rims that I currently have on there, so I wanted a different style. And while I only have 16”, I was told by multiple sources (friends, and my mechanics) that I can go up a size on them. However, from what you’re saying it seems as if I do go up a size, it won’t handle the same. That’s not something that I want whatsoever. I’d like to cosmetically improve the look, but don’t want to sacrifice the handling of the vehicle.

Hope that helps. What do you think?
 

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Thank you for chiming in. I don’t like the rims that I currently have on there, so I wanted a different style. And while I only have 16”, I was told by multiple sources (friends, and my mechanics) that I can go up a size on them. However, from what you’re saying it seems as if I do go up a size, it won’t handle the same. That’s not something that I want whatsoever. I’d like to cosmetically improve the look, but don’t want to sacrifice the handling of the vehicle.

Hope that helps. What do you think?
You can definitely go up a size and keep handling the same. Typically, most people on this forum aren't into changing too much on their car like wheels. But going up to even an 18" won't change handling too much as E46s had 18" an option (specifically 225/40R18 AND 255/35R18) which were on 18x8 and 18x8.5.

Personally, I am running an 18x9 ET42 square setup and haven't lost any handling, in fact, it handles so much better than stock. I've also run 18x8.5 ET38 and 18x9 ET42 staggered setup with no changes to handling. As long as you're not stretching tires you won't ruin the handling.
 

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Discussion Starter · #20 ·
You can definitely go up a size and keep handling the same. Typically, most people on this forum aren't into changing too much on their car like wheels. But going up to even an 18" won't change handling too much as E46s had 18" an option (specifically 225/40R18 AND 255/35R18) which were on 18x8 and 18x8.5.

Personally, I am running an 18x9 ET42 square setup and haven't lost any handling, in fact, it handles so much better than stock. I've also run 18x8.5 ET38 and 18x9 ET42 staggered setup with no changes to handling. As long as you're not stretching tires you won't ruin the handling.
Got it. Thanks for the word.

I like the style of the rims that I shared, so trying to go with that vibe. Just trying to learn what I can do and can’t do because of sizing restraints.

For example, I found these which are 205/55/r16 91h. Would those fit my car?
917948
 
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