[solacebmw]

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I just switched from 156 (16" oem) to the staggard 161 (17"). Does the extra weight of the 161s and their extra width affect performace? I feel the car is slightly less lively after the switch. I do feel the steering has gotten an hair tighter, especially at highway speeds. Any thoughts?

[solacebmw]

sorry, wrong forum.

[ase2dais]

Originally Posted by solacebmw

I just switched from 156 (16" oem) to the staggard 161 (17"). Does the extra weight of the 161s and their extra width affect performace? I feel the car is slightly less lively after the switch. I do feel the steering has gotten an hair tighter, especially at highway speeds. Any thoughts?

I didnt think so, but mine are non-rft's, its quite an improvement in fact

edit: rft are heavier

[- Paul -]

More rotational mass or is that weight?? = slower acceleration but yes you're correct - wrong forum

[PocketRocket]

you cant possiblity go slower , you are just feeling more road hug

[- Paul -]

Originally Posted by PocketRocket

you cant possiblity go slower , you are just feeling more road hug

Wrong - more weight in the wheel is more to turn = slower

The only way round this is to buy light wheels.

[PocketRocket]

Are you saying that 325i ZSP e90 cars are slower than 325i nonZSP then ?

I'll like to see this at the tracks!

[- Paul -]

Slower round a track or slower in a straight line? (eg 0-60) Correct me if wrong as I'm from the UK but doesn't the ZSP have sports suspension?

[canucklion]

I think stock to stock, the ZSP would be slower than non ZSP in straight line (though probably minimal difference), and the ZSP would be faster than non ZSP on track; due to upgraded suspension bits + wider rear tires.

Originally Posted by PocketRocket

Are you saying that 325i ZSP e90 cars are slower than 325i nonZSP then ?

I'll like to see this at the tracks!

[E91AWD]

It's not just a question of how much a wheel weighs. It's also important to know how the weight is distributed. Weight close to the center of the wheel is not as bad as weight on the tire. I'm sure this has been discussed to death before.

[Chesmu]

ksfrogman lost 1-2 rwhp when he switched to bigger tires, likely secondary to the energy required to get a heavier tire spinning. Yes, bigger, heavier tires will slow you down.

http://www.e90post.com/forums/showth...ight=reclaimed

[Josh49]

I did this same exact change and felt the same exact thing you are feeling. When I put my 156's on for the winter again, I felt the opposite happen. The 161's weigh more, both because the diameter of the wheel is larger, but also, the wheels are a lot wider. The 156's look like pebbles compared to the rear 161's width wise.

Moment of inertia increases as the square of the radius (I = m r^2). So as you push the metal out from the center, you are increasing the rotational inertia more and more. Heavier wheels/rotational inertia will accelerate and decelerate slower. The car is slower with the 161's on.

It's a tradeoff though, because you gain a lot in traction. Those 161's grip like hell, the new traction is delicious..

[CnoteMD]

I have a set of 17 inch ASA JH3 wheels with Dunlop snow tires (RFT). When I put these on for the winter, my acceleration feels a little more responsive. However, there is definitely a trade off as far as traction is concerned. In general, larger and/or heavier wheels will result in slightly slower acceleration. However, when my 18 inch Style 162 wheels with RFT's are put back on in the spring, there is definitely more of that power getting to the road.

If you upgrade from 16 inch all-seasons to 17 inch summer tires, whatever losses you experience due to weight are probably balanced by the increase in traction. But as the weight continues to increase (i.e. even larger differences sizes/weight) then you will likely continue to lose acceleration.