Sponsored by The Tire Rack

[rai]

Originally Posted by BCMPOWER

My only concern is the wear rate of the performance winter tires. I was suggesting you use the Pilot A/S as your cold weather tire and not sacrafice wear, road noise and some dry weather performance.

In my experience with winter-performance tires wear much like an AS tire (not like a real ice/snow tire where the soft tred wears off quick).

The Wintersport tires I have on my S2000 wear twice as long as the summer tires so they are good for ~4 seasons.

It saves wear on the summer tires which cost more and last less. I would say the saving of wear on expensive summer tires would pay for the extra rims.

[GregW / Oregon]

Originally Posted by rai

In my experience with winter-performance tires wear much like an AS tire (not like a real ice/snow tire where the soft tred wears off quick).

The Wintersport tires I have on my S2000 wear twice as long as the summer tires so they are good for ~4 seasons.

It saves wear on the summer tires which cost more and last less. I would say the saving of wear on expensive summer tires would pay for the extra rims.

I use my SUV when the weather is really nasty here, which is not that much.. That said, I espouse the principal of maximum performance summer or winter. I have max performance summer tires for my MlL (pictured) and Pirelli Scoripion Ice & Snows for winter. Changing wheels takes 35 minutes. I like to be prepared for whatever the conditions.

[sayemthree]

BTW I just weighed my 19's and got the exact same weights as Greg!

[12:03]

So the 19s are lighter, but wouldn't the 18s perform better, because of the larger sidewall and the tire being more rubbery than the 19s? It seems the theory is such anyway

[sayemthree]

Originally Posted by 12:03

So the 19s are lighter, but wouldn't the 18s perform better, because of the larger sidewall and the tire being more rubbery than the 19s? It seems the theory is such anyway

depends on factors. sometimes the stiffer sidewall is better. on a bumpy surface the taller tire my stick better but then with the EDC equipped M3 that may be irrelevant. in raw acceleration the lighter wheel would win. in handling, less wieght is always an advantage too. with wheel/tires that are both unsprung and rotating mass the weight advantage of a few pounds is multiplied.

[Moderato]

IMO the 19's look way better, not just the size but the actual design of the wheel and how they suit the car. If the 19's don't weigh anymore then the 18's then I like them even better to me. IIRC, with the E46 M3 the OEM forged 19's did weigh more then the cast 18's. I had an E46 M3 with the OEM 18's and also an E46 M3 with the ZCP 19's and I did notice the ZCP's felt just as agile and light, if not more so then the OEM 18's. Wheel weight does matter and it is noticeable. If I were to order an E92 M3 today, without a doubt I'd go for the 19's, better looks and the same weight!

[sayemthree]

Originally Posted by Moderato

IMO the 19's look way better, not just the size but the actual design of the wheel and how they suit the car.

I agree of course its all personal taste. but the e92 is a bigger car than the e46 and 18's tend to look a bit small.

[Moderato]

Originally Posted by sayemthree

I agree of course its all personal taste. but the e92 is a bigger car than the e46 and 18's tend to look a bit small.

Yeah right, that's what I'm saying the 19's look better on the E92 and also on the E46 M3, IMO for that matter.

[sayemthree]

word!

[urbo73]

Originally Posted by sayemthree

based on the info from GregOregon and badfish and Tire rack

19's
f = 23
r=26.5

18's
f=25
r=25

Originally Posted by GregW / Oregon

I think with numbers this close, the weight comparison is a nonissue. People need to go with what they like and use whatever other criteria they have to make a decision. If there was 4 or more lbs. per assembly difference, then you could start to think about it. Personally, I will only go with forged wheels because they will hold up over the long haul.

Originally Posted by sayemthree

x2.

except being a track junkie I like that the 19's have 4 #'s less unsprung and rotating mass.

I went with the 19's - merely cause I thought they looked better. and I like the idea they are forged.

I was searching and finally saw these numbers. While the differences may be small, most of the weight of the wheel is not in the spokes but in its radius/inside wall. So a wheel with a smaller radius is easier to move. In which case I see no advantage to having the 19" other than looks. If you are indeed a "track junkie" use the 18"s. No sense at all in using the 19"s.

[swamp2]

An interesting part of this is the numerous results we've heard about the 18s ever so slightly outperforming the 19s. Seems if we believe such tests it is the moment of intertia effect, not the weight.

[jk6672]

if you want to reduce weight try these

[urbo73]

Originally Posted by swamp2

An interesting part of this is the numerous results we've heard about the 18s ever so slightly outperforming the 19s. Seems if we believe such tests it is the moment of intertia effect, not the weight.

Exactly! The weight difference being negligible, moment of inertia is what counts. And though I don't know the precise weight *distribution* of the 19" OEM wheel (and thus can't say what 19" wheels would need to weigh to perform the same as the OEM 18"s - the difference would have to be pretty large), I do know that it will have most of its weight (mass) towards the outside of the hub. So it will have a higher moment of inertia and thus be more resistant to acceleration since I=mr^2

This is why smaller wheels are better in racing/track/etc. Only go as big as you need to clear the brakes, etc. Or go big for looks.

[sayemthree]

Originally Posted by jk6672

if you want to reduce weight try these

you mean if you want to refuce your wallet!!!!!!!!

[sayemthree]

Originally Posted by urbo73

I was searching and finally saw these numbers. While the differences may be small, most of the weight of the wheel is not in the spokes but in its radius/inside wall. So a wheel with a smaller radius is easier to move. In which case I see no advantage to having the 19" other than looks. If you are indeed a "track junkie" use the 18"s. No sense at all in using the 19"s.

or is there more weight in the FAT 18 inch tire?

[RandyB]

Originally Posted by urbo73

Exactly! The weight difference being negligible, moment of inertia is what counts. And though I don't know the precise weight *distribution* of the 19" OEM wheel (and thus can't say what 19" wheels would need to weigh to perform the same as the OEM 18"s - the difference would have to be pretty large), I do know that it will have most of its weight (mass) towards the outside of the hub. So it will have a higher moment of inertia and thus be more resistant to acceleration since I=mr^2

This is why smaller wheels are better in racing/track/etc. Only go as big as you need to clear the brakes, etc. Or go big for looks.

I believe it's the heavier 18" tires that tip the scales in favor of the 19" combo, so there goes that moment of inertia thing since they are out past the wheels in distance from the center.

[urbo73]

Originally Posted by RandyB

I believe it's the heavier 18" tires that tip the scales in favor of the 19" combo, so there goes that moment of inertia thing since they are out past the wheels in distance from the center.

This may be true if the weight difference were large enough, as I said. But it hardly is. The 18" PS2s are 24/27lbs F/R and the 19" PS2s are 24/25lbs F/R. So total savings are 4lbs on the rears. Hardly enough weight to overcome the larger radius of the 19" wheels on all four corners which have most of their mass towards the outside - this is the bigger factor. When things are just about equal - like they are here - the 18" (or smaller radius wheel) will always have a lower moment of inertia. Hence they will perform better. How much better? For the average driver they won't even notice. To me, the 18"s make the most sense on this car. Smaller wheels are most always better when you need performance - car performance that is

[swamp2]

Originally Posted by urbo73

This is why smaller wheels are better in racing/track/etc. Only go as big as you need to clear the brakes, etc. Or go big for looks.

I agree, but only if you are an absolute purist. The overall performance difference will likely be smaller than car to car and certainly smaller than driver to driver variation. To me 19s are a good compromise. The car looks kind of large and 19s fill out the wells better with only a very small performance hit. 20s in the other hand...

[sayemthree]

i think the point is that BMW did the RIGHT thing by making the optional (more money) 19 forged wheel combo actually save weight.

[urbo73]

Originally Posted by swamp2

I agree, but only if you are an absolute purist. The overall performance difference will likely be smaller than car to car and certainly smaller than driver to driver variation. To me 19s are a good compromise. The car looks kind of large and 19s fill out the wells better with only a very small performance hit. 20s in the other hand...

True, but IMO the 18" ride better as well.

[sayemthree]

Originally Posted by urbo73

True, but IMO the 18" ride better as well.

so does a Lexus? your pont?

[swamp2]

Originally Posted by urbo73

True, but IMO the 18" ride better as well.

Yup, forgot about ride, definitely will be a bit better on the 18s!