E46 wheels and tires

Now THAT makes sense! Thanks for clearing that up.

Nels

Reply to
Nelson J. Starbranch
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So, not wanting to beat a dead horse to death, you have 17 x 7.5 front rims and 17 x 8.5 rear rims? These rims are the same size as what comes on the M3, but your rims are not specifically M3 rims, right? I am just wanting to get the picture straight because as I follow this thread, I never get the feeling that these questions are answered. I think I get it, but I just wanted to be sure that everybody else gets it.

My point being that I had said earlier that IF there was any potential for problmes with M Series rims on a 330, then the troubles would be at the rear, and the tires would rub on the fenders. You have made it clear that your tires do not rub on the fenders, and that you have a 330, but you really haven't made it very clear that you have the wide tires. Others have said that there are geometry issues, but I don't think this is true at all. I also don't think the tires will rub on the fenders, but that is where I would focus my attention if I was making this change. My car is a '94 325, and I put M Series rims on it, but I have four 17 x 7.5 rims - 5 counting the one in the trunk - so I haven't got the stagger sizes going on with my car.

I just wanted to bring all of this crap together so the OP would go out and buy his new rims and get on with it.

Reply to
Jeff Strickland

18X8 front, 18X9 rear. Remember, this is an E46, not an E36. My rear tires are 255/35ZR/18's. I think the stock tire size was 255/40/18. I'm going on memory here so take what I say with a grain of salt. Also, I am relatively new to the BMW experience.

These rims are the same size as

As was so rightly pointed out to me, they are BMW rims, they are "M" rims, but, they are not, in fact, M3 rims.

I am just wanting to get the picture straight because as I

You have done a good job of it. ;-)

Yes. I have 255's. I do not think the 19's (optional M3) would fit. I'm not even sure if the 255/40/18 size would fit. I do not rub anywhere but it's pretty close in there.

Others have said that there are geometry

As stated, good job. I just hope I haven't added any confusion with my fumbling. ;-)

Jeff

Reply to
Jeff Mayner

Sorry, my error. The topic is and has always been about 18" rims, not 17s.

Thanks for filling in the details.

Reply to
Jeff Strickland

If someone would actually help to answer my question instead of lecturing me on why I shouldn't, the stock sizes, poor ride and such, I would stop asking the question. My question is simple: What is the widest tire I can put on the rear of my car without rolling the fenders? That's all. I expect to use wider rear wheels to accomplish this. 18x9 perhaps. So, has anyone out there managed to get an 18/275/45 on an '01 330ci? If you have (or haven't because there was an interference issue), I'd like to hear your story. Why do I want to do this? I just like the look and I fully expect to end up with a great handling car. I'm not concerned with a reduction in ride quality as it couldn't be worse than what I have right now (Sumitomo SU HTR+ 245/40/17. Very noisy tire). Keep in mind I don't race it. Just spirited, every day driving. TIA for all of your "useful" answers.

Reply to
Planar1

I don't know the answer to your question, exactly. But, I do know you need to do the math to arrive at the answer.

First, the tire size is always expressed as 275/45x18, where the width is first, the aspect ratio is second, and the rim size is third. Any other expression of tire size will just confuse whoever you are talking to.

Second, multiply your CURRENT width by the aspect ratio to arrive at the size of the side wall, then double this number and add in the rim diameter to arrive at the overall diameter. Then rework the calculation in the same way, reducing the aspect ratio and increasing the rim diameter to see if the tires you want are even remotely close to the diameter of the tires you have. If the overall diameter is different, the gearing will suffer and the speedometer will be out of calibration. If you new size is within a few percent, then you have hit the nail on the head, but if off by more than an inch, you will feel the difference.

The width of the tires you want will be constrained by the width of the rims that are available. If you want factory rims, the rear will be capped at about 18x9 or maybe 19x9. I posted a link to the many different rim options that you can get through BMW, but I didn't look closely at the list and my reocllection is that the 3 Series gets an 18 as the largest rim, but I could be wrong on that. The list gives the tires size that fits the rims, so it really is a valuable resource for your question.

My car came originally with a 225/55x15 -- I have a '94 with the Sports Package. I recently changed to a 17' rim because the tires in the equivelent size are much cheaper, and there are many more choices if I wanted to spend the same amount of money. The original tire was made by one tire company, the replacement tires are made by at least a dozen companies. My new tire size is a 225/45x17, and the diameter went from 25.02 to 25.20 inches. The difference in the diameter is less than a quarter inch, and just a bit over a half inch on the circumference, which is what you want to come to.

If you want to move away from BMW rims and go to aftermarket offerings, then I suggest you look at the BMW options, find what goes on an M3 for the year of your car, and use that as your guide.

The 275s that you want work out to be just over 11 inches wide. To remain within the diameter of your stock tires, you are going to need an aspect ratio of about 30 if you put them on the 18 inch rims. A 275/30x18 will give you an overall diameter of 24.7 inches. This is very close to stock, and the speedo and the gearing should tolerate this easily, the big question remains, will they fit inside the fenders? Personally, I don't think a 275 fits on the stock rims, but that's me. I think you will find your tires constrained to about a 255/35x18, or maybe a 255/30x18. These will give you a diameter of 25.25 or 24.19 respectively. One consideration whenthe sidewalls become very narrow is that the tire's width has to match the width of the rim. When the sidewalls are very large, then there is more room for tires that are wider than the rim to accomodate the buldge. When the sidewalls get very narrow, you really want the tires to be only about a half inch off of center (an inch overall) wider than the rim. If my math is correct, a 9 inch wide rim will take a 225 wide tire, observing the rule that the tires should not be more than about an inch wider than the rim, the

255s would be about as wide as you could go.

Bottom line, I think you will find that you can put a 255/30x18 or 255/35x18 on your car. These should fit fine without rolling the fenders. If you find a 19 inch rim, then a 265/30 will give you a diameter of 25.4 inches. While the diameter is a bit large, I think the width will present rubbing issues.

Of course, I am not even considering stagger - different sizes on the front and rear -- I am only looking at the max size that the rear can take, the front should take a narrower tire, but you seem to be expecting that. If you can't do the math, there are several tire size calculators on the 'net that can help you convert from the size you currently run to a size that you dream about.

Here is the BMW Rim Option link that I gave you several weeks ago,

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Reply to
Jeff Strickland

Maybe try calling

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They've got a lot of factory specs at hand and have always been a good source of info. Maybe not to buy from them but at least for the knowledge. Pretty easy to talk to a real person.

Reply to
dwilli

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