Is going from 17" to 18" worth it?

I have a 28i without sports package or dynamic handling package.
It has the standard 17” wheels.

We’ve been having some very windy days (25mph +) and I’ve noticed it makes the car slightly wobbly at least when compared to my previous BMW's.

I’m wondering if going to an 18 inch wheel with the resulting lower profile sidewall would help this in any respect, or is what I’m feeling just a result of the suspension. I don’t want to go larger than 18” as I still want to keep ride quality a priority (we have terrible roads here).

Can I expect the dealer to give me something on trade in on my original set of wheels (approx 200 miles on them)?

Originally Posted by harplayr

I have a 28i without sports package or dynamic handling package.
It has the standard 17” wheels.

We’ve been having some very windy days (25mph +) and I’ve noticed it makes the car slightly wobbly at least when compared to my previous BMW's.

I’m wondering if going to an 18 inch wheel with the resulting lower profile sidewall would help this in any respect, or is what I’m feeling just a result of the suspension. I don’t want to go larger than 18” as I still want to keep ride quality a priority (we have terrible roads here).

Can I expect the dealer to give me something on trade in on my original set of wheels (approx 200 miles on them)?

I would attribute the wobbly feel to the fact that the vehicle is alot taller than a car. It is natural for trucks and SUV's to be a little more "tippy".

If you do go with 18" wheels, I would be interested in your stock 17" wheels for winter tires.

it should not make a diff and no, he won't give you anything for your wheels....

Originally Posted by Cactus

I would attribute the wobbly feel to the fact that the vehicle is alot taller than a car. It is natural for trucks and SUV's to be a little more "tippy".

If you do go with 18" wheels, I would be interested in your stock 17" wheels for winter tires.

As far as the wobbly feel, I’m comparing it to my previous generation X3 that I traded in and not a car.
I know that it had a much stiffer suspension, but I’m looking for a happy medium.

Overall I’m very pleased with the F25’s ride quality, and in most conditions am fine with the handling but I was looking for just a little bit more side to side stiffness for those very windy days. I was wondering if by going to a slightly lower profile tire if it would provide any measurable improvement in that regard without sacrificing too much of the ride quality.

No, a larger wheel size won't affect stability. The DHP and sports suspension (not available in North America) would hunker things down a bit.

Originally Posted by AzNMpower32

No, a larger wheel size won't affect stability. The DHP and sports suspension (not available in North America) would hunker things down a bit.

I was going on the theory that tires can have an impact on handling and that larger profile tires would have a little more play laterally than smaller profile tires. I may try putting a couple of extra pounds of air in them to see if that has any impact.

As far as getting different options, that’s a non-starter. The car has already been built.

The Variable Steering (also part of DHP) probably would also help. I felt the electric steering in the X3 was a bit lifeless and overboosted, which can contribute to a bit less driver confidence even in a straight line.

The difference in sidewall and flex is really not going to show up until you corner really hard and start squealing the tires. You'd be going from a 55- to a 50 sidewall aspect ratio, hardly a change. The base versions in Europe get a more comfortable ride with non-RF and P225/60R17 tires as standard. Going from those tires to the 18" might elicit a more noticeable change.

I increased tire pressure from the recommended 32psi all around to 35psi all around and it did seem to improve handling a bit, a little more "connected" feeling and didn't impact ride quality noticeably.