Lighter wheels = Rougher ride?

[P6GTD]

I’ve replaced my (heavy) standard Parker’s with aftermarket alloys approx 2kg per wheel lighter. Same size 18” and width as the originals.

Much has been made of the virtues in reducing unsprung weight.

But the only discernible effect for me is a rougher ride on most surfaces.

My car has DCC and each of the settings seems to give a ride about 10% rougher than with the heavier wheels.

I’ve searched this and other forums before posting as there doesn’t seem to be any comment other than on AI which suggests a rougher ride may indeed be the result of a lighter wheel causing the suspension to react more eagerly (sensitively?).

Any opinions or experience?

[MinchCS]

If you ask AI this in different ways you get opposing answers: sometimes it says it makes ride harsher, other times more comfortable. That's AI for you

I have made the change twice. Both to OZ (leggera and ultraleggera). Once on a 997, with the same tyres switched over, and the ride was better.

And on my Clubsport S and the ride is leagues better BUT on this one I went from 19 prets to 18 OZs saving 2kg a corner, and had new tyres so those two probably explain much of the improvement.

Have you changed the tyres too? There is a lot of sidewall stiffness variation between makes - even with same load rating.

[P6GTD]

Thanks Minch. I put 4 new Goodyear AS6 on at the same time.

Had PS4 set before. Goodyears seemed to get a slightly better review for ride and noise. Certainly quieter but I’m perturbed by the jittery suspension.

I wonder if DCC doesn’t understand what’s going on (that’s a half-joke)?

Anyone else help?

[MinchCS]

I reckon the tyres are the issue, particularly during wet and cooler weather. Mich PS4S has a very comfortable ride for a sports tyre - unlike the Mich supersports - and I would be very surprised if the Goodyear are not stiffer. Is the load rating the same?

[SRGTD]

@MinchCS; My initial thought was tyres too when I read @P6GTD’s initial post.

[mcmaddy]

Michelin PS4 are a softer less sporty feel than the Asy 6 and I couldn't wait to get of rid of mine.
The firmer sidewall will make a difference but it should be slightly more sharper rather than crashy.

[P6GTD]

Thanks all…this is indeed sounding like change of tyres after running Michelins for quite a few years

[EB2019]

The theory as far as I know.
Heavier wheels will generally deflect less over small imperfections and force the tyre to absorb more. Add softer sidewall tyres PS4 and this should increase the absorbing of small impacts (a little).

Lighter wheels should deflect more easily and combined with stiffer sidewalls will transmit this into a slightly more nervous feel or slight NVH.

This is the only slight positive for heavier wheels, compared to lighter wheels over small imperfections. But I don't think it remains the same for large bump/rebound of the suspension, where lighter wheels helps to keep the tyre on the road as the rebound of the damper/spring has an easier time forcing the lighter wheel back into the tarmac. I think the theory goes...


practically it feel like this to me to, I put my Milton's back on this week and its a slightly softer ride with PS4, but they also feel like boat anchors at each corner and the car feels less agile. 

[P6GTD]

That’s interesting and makes sense. Yes, the car feels a bit “jittery” and also, as I alluded to a few posts ago, I wonder what part DCC plays as its “on” all the time.