Mr. Grinch

Full credit goes to Jason, Ced, RS2, regulars in bimmer.org, who did much of the leg work to gather this info for 17" winter wheels.

GIVEN:
Factory M3 wheels in North America are not optimal for winter use. They are very low profile, which is not the best for snow and ice. It is very hard to find winter tires for the factory 18" size.

Factory 18" for North America (No Factory 19" here)
Front: 18"x8", 47mm +offset, 72.5mm centerbore
Rear: 18"x9", 26mm +offset, 72.5mm centerbore

GOAL:
Find some winter wheels for the M3.

PREREQUISITES:
- Inexpensive
- Good Fit
- Look nice
- Availability
- Sized appropriate for snow / ice. 17"x8" gives a higher profile. Higher profile is better for these conditions.


BMW OPTIONS:
M68 E46 M Sport wheel or M2 Double Spoke wheel:


36-11-2-229-480 front 7 1/2 x 17 offset 47 mm
36-11-2-229-980 rear 7 1/2 x 17 offset 25 mm

- Supposedly does not require spacers or centering rings

- $850 CDN each or about $600 USD. Very expensive. One person found a dealer to sell them for $300.
http://forums.roadfly.com/bmw/e46m3/...153862&page=10

- Looks are not appreciated by many

- Other places sell cheaper replicas. Here is one at http://www.discounttiredirect.com



TIRE RACK OPTIONS:
http://www.tirerack.com

Sport Edition Valore 17"x7" $129 USD each


Sport Edition Tekno 17"x7" $129 USD each


AT Italia Type 5 17"x7.5" $183 USD each


- Require lateral spacers and extended lugs for proper offset

- Spacers are not always trouble free. Known for causing shimmy or vibration problems at speed. During mounting, the wheel may not be centered about the hub due to the spacer.

- Wheels must be torqued without the weight of the car on them to try and reduce this problem.


DISCOUNT TIRE OPTIONS:
http://www.discounttire.com
http://www.discounttiredirect.com
Many options listed.

M3 Replica wheels $205 USD each


M3 Replica front 17x8", 47mm offset, 72.5mm centerbore, perfect fit.
M3 Replica rear 17x8", 20mm offset, 74mm centerbore, requires centering rings kit.

- Apparently they have a good, tight fight with the rings, and centering rings are not known to have the same issues as spacers which affect lateral adjustment.


WHEEL EXCHANGE OPTIONS:
http://www.wheelexchange.com

M3 Replica


Seem to sell 17" wheels similar to Discount Tire. However, in email correspondence, the M3 replica fronts are listed as 41mm offset, and in other ebay postings from same seller, listed as 47mm offset. 47mm is the same as stock M3, so it's prefered. But Jason and myself could not seem to get a clear answer on which ones WheelExchange was selling.

Jason went with the Discount Tire ones... I think he's happy with them... waiting to hear more.

I have abount a month before I need any... will still have my other car for a while yet. I'm holding off and waiting to see how Jason and other people find their new wheels to be.

If I had to buy right now, I would lean towards Discount Tire Direct, M3 Replicas. Apparently they ship to Canada. This would be about $2200 CDN for wheels and tires, vs the dealer who wants $3200 CDN. Both prices quoted before tax.

Other wheel images:




17" WINTER TIRES:

- Current popular recommendation is 225/50R17

- BMW Manual says 225/45R17 but nobody knows why. This size is 4% too small by our calculations. Perhaps this is for tire chain clearance?
- Everyone else suggests 225/50R17 for closest possible outer diameter and highest profile.

- Some options are Blizzak MZ01, Pirelli 210

- There are also chains available:
http://www.vulcantire.com/chain.htm

I could not find chains for low profile 18" but I did find some for 225/50R17.

johann

Mr Grinch,

Thanks very, thorough.

I agree that 18" tires are harder to find but why would they not be good on ice and snow?

Cheers,
/Johan

Mr. Grinch

18" winters in factory size would still be better than the 18" all seasons, just not as good as something higher profile.

The profle of the tire helps determine the shape of the contact patch. A low profile wheel / tire has a wide, side to side, oval contact patch. A high profile wheel / tire will have a narrower contact patch that is longer, front to back.

A narrower contact patch is better on snow / ice. It cuts down into the snow lower, instead of sitting on top. It also tracks better in the ruts left by other cars, better than a wide contact patch.

A low profile tire has a stiffer sidewall. A higher profile tire has more flex. In slippery conditions, a tire with more flex has a better chance on an uneven surface. It also copes better with frost heaves, bumps in the road due to expaded frozen moisture in the ground.

Also, I've not yet seen chains for the 18" size, and probably this is difficult because they need to come up the sides of the tires, and on 40 series rubber there isn't much sidewall to come up.

johann

OK,

I agree to a certain point. but there is not not much difference in a 45 profile tire and a 50 profile tire, is it?
I.e a 225/50-17 vs a 225/45-18.

What have tire profile to do with the width of contact patch?
Aren't we mixing width with profile?

I still agree that a higher profile tire is better but to really make a difference you should use a narrow 60 or 65 profile on 16 or 15 inch rims (which isn't impossible). Of course 50 is better than 45.

What really matters is that the tire is coposed of a rubber mixture that still provides friction in cold temperature and with still is decent on dry and wet roads.

Cheers,
/Johan

Cosmos

I would look into just getting stock 18" wheels used for about $1200, that way you know they will fit. Or my personal favorite, just go for 19" summer wheels, that way you get free 18" winter wheels from the factory.

__________________
"Motion does not equal progress"...Cos
Malo periculosam libertatem quam quietum servitium...

Mr. Grinch

Well, problem with a factory sized winter tire on this side of the ocean is probably the biggest reason I did not mention it, but if you have sizes and brands, then we should definately include them.

There is also the fact that you can't get chains for them. I don't drive too often in the mountains when it snows but weather can change in an instant, and we have enforcement of chain laws here when it's really bad.

Speaking for myself, I have had occasion to use chains about once or twice every winter. With them, I've been able to go places where full sized 4x4 SUVs could not go! Definately handy.

The shape of the contact patch is always important. Higher profile makes a longer contact patch, given two tires with the same width. Looking at the factory rears, going from a 40 to a 50 series definately will make a difference, no question about it. (partly from wheel diameter, partly from narrower tire).

It would make as big a difference as going from 50 to a 60, which I do have experience with, and think is quite an improvement for snow / ice traction.

What I've heard is that the M3 brakes, which are the same size as the M5 brakes, simply are too big to house 16 inch wheels. Any attempt to push them out for clearance would require spacers... something I think I'll try and avoid given some of the potential problems I've heard about.

I agree with Cosmos, if you already have 19" then the 18" might make reasonable winter wheels, depending on your road conditions. (We don't get 19" here either). I'd like to get some forged wheels at some point for summer but just can't justify the cost right now.

Then there is the cost factor, for some it's hard to justify the cost of a wheel that will be destroyed by sand, gravel, salt, or curbs hidden by snow. Of course, the 17" tires are cheaper too.

As you hinted at, every tire is a compromise. A higher profile, soft "ice" compound winter tire will indeed leave you feeling disappointed with the wet/dry handling compared to the factory tires. But if the depth and longevity of the snow where you live is bad enough, you may feel the sacrifice for handing is worth the extra traction when you're on snowed-in roads.

We do get those conditions here, although only for a month at most usually. During that time, it really is amazing to have the highest profile, softest ice tire you can get. The rest of the time, a low profile winter tire with firmer dry / wet handling, is much better, like you said.

Mr. Grinch

Cosmos:

http://forums.roadfly.com/bmw/e46m3/...=171833&page=1

johann

Mr Grinch,

Now you made me consider 17" rims again.
I still don't get why a tire of similar width would have a longer contact patch because it has higher profile. Can you explain it ,please?

Cheers,
/Johan

Mr. Grinch

The distribution of weight on the contact patch is oval. The profile has an effect on the shape of that weight distribution.

Take for example a super low profile... like 10 or lower. The lower you go, the closer the tread is to the wheel. The closer the rubber is to the wheel, the shorter the sidewall, the less room it has for front/back deflection. In effect, what you have is a metal cylinder covered in rubber now. The footprint will basically be a line from one side to the other (left to right).

Now go the opposite way. Increase the profile to 100. The higher the profile, the further the rubber tread is from the wheel. Instead of being pulled close to the weel, the much higher sidewall allows more deflection in the front / back direction. Contact patch will be longer front to back.

Basically, the lower the profile, the more a tire is forced to behave as a perfect cylinder, which has a contact patch of a straight side to side line. The higher the profile, the more the tire can flex, shaped like a torus, or donut, allowing a longer front to back weight distribution.

Of course with a higher profile you can get away with lower pressures too, because you have more volume and more distance betwen the road and wheel. This allows not only the contact patch to change shape, but to be bigger too.

I should add, that many "winter" tire makers use a round casing (more donut shaped instead of flat cylinder shaped like a race tire). On a dry road, this isn't as good for handling, but on snow/ice, this again gives a longer contact patch which is better. I know Yokohama does this on their GuardX tires. So even if you do decide on same size tire as summer, you can change the shape of the contact patch with a different casing shape.

But everyone's driving conditions differ. For me, I definately hate the squishy handling of my winters on my current car. However, the two weeks I had to take them into very, very deep snow last year, going where many cars could not, were worth it.

The question is, could I have done the same with a lower profile tire, given both without chains? Given some of the times I was almost stuck, I'd say the car was pretty close to the limits of traction. We are talking conditions where you have to start in 2nd gear because traction is so low. So I wonder myself what it would be like to compare them side by side. Again, the cost and availability are factors for me as well. Then there is the other option... just leave it parked!

Ossi

My experience clearly shows that 18" winter tire is as good as 17" . In fact overall 18" is better.WE have real winter here and I've driven more than 40000km in winter with M5 and there is really no point to downsize tire to 17", no matter what theory says.

Although this is only my personal experience I don't see point downsizing tire too much. 17" will be fine with 225/45/17 but why not try 235/45/17,it's diameter is only 2,5% smaller than standard tire. But best compromise for M5 and why not to M3 is 18" all the way.