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Looking into upgrading my 525i to 730li. Dealer says 17 inch wheel size comes standard with my desired model. Are 17 inch wheels going to be stable for such a large car? He's saying that since our roads have way too many potholes, smaller wheels are going to be more comfortable. It has a 2.0 liter i4 engine, but that's fine since I will mostly use it in the city.
 

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I've never driven a 7 series with 17 inch wheels, but the pothole argument doesn't make much engineering sense on the surface. The smaller the wheel, the more likely it will be to drop into a modest sized pothole. Think of it in the context of what a really large diameter wheel would do with a pothole - it would bridge the hole if it was large enough (though that's not practical). Now think of a really small diameter wheel (like 6 inches) - it would be bottoming out in every pothole that was larger than 6 inches diameter. It seems to me that a smaller wheel would offer a more jarring ride ... if potholes are an issue.

BUT the smaller wheels may be more responsive with a smaller engine than what's common here in the US since it takes less torque to get them moving. My suggestion, drive what you are considering several times over an extended mix of roadways. See if you like it. Then try to drive one with 18 or 19 inch wheels and compare the ride on the exact same course. I did that 3X in a 740, a 750 and my old MBS550 before deciding I liked the 750.
 

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I've never driven a 7 series with 17 inch wheels, but the pothole argument doesn't make much engineering sense on the surface. The smaller the wheel, the more likely it will be to drop into a modest sized pothole. Think of it in the context of what a really large diameter wheel would do with a pothole - it would bridge the hole if it was large enough (though that's not practical). Now think of a really small diameter wheel (like 6 inches) - it would be bottoming out in every pothole that was larger than 6 inches diameter. It seems to me that a smaller wheel would offer a more jarring ride ... if potholes are an issue.

BUT the smaller wheels may be more responsive with a smaller engine than what's common here in the US since it takes less torque to get them moving. My suggestion, drive what you are considering several times over an extended mix of roadways. See if you like it. Then try to drive one with 18 or 19 inch wheels and compare the ride on the exact same course. I did that 3X in a 740, a 750 and my old MBS550 before deciding I liked the 750.
When they change the size of the rim the outside diameter of the tire is usually the same by varying the sidewall height. A 17" tire will have more meat on the sidewall protecting it better from potholes....
 

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I've never driven a 7 series with 17 inch wheels, but the pothole argument doesn't make much engineering sense on the surface. The smaller the wheel, the more likely it will be to drop into a modest sized pothole. Think of it in the context of what a really large diameter wheel would do with a pothole - it would bridge the hole if it was large enough (though that's not practical). Now think of a really small diameter wheel (like 6 inches) - it would be bottoming out in every pothole that was larger than 6 inches diameter. It seems to me that a smaller wheel would offer a more jarring ride ... if potholes are an issue.

BUT the smaller wheels may be more responsive with a smaller engine than what's common here in the US since it takes less torque to get them moving. My suggestion, drive what you are considering several times over an extended mix of roadways. See if you like it. Then try to drive one with 18 or 19 inch wheels and compare the ride on the exact same course. I did that 3X in a 740, a 750 and my old MBS550 before deciding I liked the 750.
Surface area is the same unless the tire is very narrow which I doubt it is. But it is better for potholes. I taller sidewall provides more cushion
 
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