The general rule of thumb is that every pound of rotating mass lost is equal to 10 pounds of non-rotating mass on a car. So if you drop 10 lbs worth of tire, it will be like dropping 100 lbs from the body. The reason is that rotating objects like a wheel require more force to accelerate. The further the weights from the center of rotation, the more force required to turn it (think of an ice skater spinning and then bringing her arms closer to her body causing her to spin faster). So run flats, which have most of their weight on the outside edge of the tire, are the worst offenders. They are absolutely the worst choice for performance but are chosen for safety reasons.

Weight is the enemy of performance, or course. Losing weight improves power-to-weight ratio, and the ruled thumb here is that every 10 lbs of weight loss in a car (non-rotating), is like adding one hp. So 34 lbs of rotating mass lost equals 340 lbs of non-rotating mass lost equals 34 hp gained. That's not even taking into account handling improvement on losing unsprung mass. I really saw a difference on my Aston Martin when I changed wheel/tires to larger but lighter ones. I saved about 15 lbs and could definitely feel it, so 34lbs will make a huge difference on this car.

I am thinking about switching to these as well. Couple of problems though
1- They are back ordered
2-The snow capabilities are questionable

They ranked an 8 something for snow. read some of the reviews. Considering the reduced ground clearance on the x5 m, I am not expecting snow cat abilitys. But an 8 ranking is pretty decent and should not get the truck stuck in most snow conditions

I am very familiar with reducing of rotating mass.
I used to race a mustang with N/A small block ford that made 902 HP. I used the lightest of all internals when it went together. rotating mass makes much more of a difference over standrad weight reduction

I think I am definitely going to the Contis all seasons. Checkout the weights

Now if I could find a local shop that would pre order me a set of matching wheels in powder coated black. Take my wheels on exchange+cost of powder coating and then mount the new contis. I would be set.

When I had my ML55, I had East Coast in Harrison order a set of chromed AMG wheels and then when they arrived, they did the swap out. It save from having the vehicle sit on jackstands and having to cart around 4 large tires/wheels. I will call Billy on Monday and see if he has a supplier that can do that.

Anyone else in NJ that does something like that?

Here is another all season:

Michelin Latitude Tour HP M&autoModClar=Built Before 10/10

Take that rating with a grain of salt. Let me know if you find these anywhere, they are still the best out there

Donho, are you planning on swapping summer and winter tires on the same rim? Some have suggested not to do that because if damage to the tire. I run the Pirelli Scorpion ice on a separate rim. Works great.

M

I am in the quest for another set of wheels right now. I do not really want aftermarket. I had aftermarket wheels on my M3 and they get hammered with the NJ roads.

I had really good luck with factory wheels. They are heavier, but they seem to handle pothole alot better.
Plus, i think I will stick with the 20's.

If I find a good set of BMW wheels with the correct offset, I will have them powdercoated in black and mount the Conti all seasons(if I can find them) and jusyt drive year round like that. I will probably just sell my factory wheels/sensors/tires.

That seems like the least amount of work. I really do not want two sets of wheels and tires. That is a pain. This is a daily driver. No need for extra work.

Just saw this. Well said and good info. Most people who get heavy replica wheels do not realize what they are getting into. Pay more for lighter OE wheels once or keep paying more for burning extra gas to chug along those heavy replicas.