Tire swap or downsize rims to improve NVH on rougher roads?

[anthony_12347]

So I've got a 2020 M4 Comp with the 20" 666 rims and the standard Pilot Super Sports, and have been looking at some options to reduce the harshness of the setup on some rougher roads.

I don't find the suspension itself too firm on the ZCP, because it's pretty reasonable even over some rougher bumps and potholes, the big bumps aren't the problem. It's the roads that have uneven pavement or rural roads with coarser asphalt that cause a lot of tire noise and harshness/vibration that can get tiring on longer drives.

Wanting to get some feedback on a couple options:
1) Keep the 666 rims, and swap to a Pilot Sport 4S, which seems to be better in the noise/comfort aspect based on a lot of reviews.

2) If the harshness is primarily the 20", drop down to the OEM 19" rim and use the P4S or Contis and benefit from the thicker sidewalls, keeping the 20" setup for track days.

Anyone with a ZCP and 20's done something similar?

[kvm-driver]

yeap from the 20's I went down to 18 inch Titan wheels, complete solution.

My basic/easy reccomendation as someone who went through the same stage, get the Michelin PS4S for your new set, they have better ride than the supersports.

I went for 18s because I track, most people in for looks go for 19s

my estimate is that 75% of the harshness is from the 20 iinch rims.
hope this helps

[Jerich0]

Our roads around here are all patched up that make them look and feel like cobblestone, that and roads that are worn and reflectors make this car vibrate like the space shuttle before takeoff, effin unnecesary BMW thanks.

As for the big stuff it is comfortable no problem.

My 18 ZCP came with 20s and swapped them for 19s with PS4 preeetty quickly. Harshness on the conditions above was reduced about 30% so not a lot, 18s don't think would make a noticeable difference because you are stuck on MPSS on those sizes (at least on tire rack)

I think the main problem is the bolted rear subframe, I still have about 1,000 miles so maybe this will get better.

If someone comes up with a bushing kit for the rear I have cash in hand.

[Jerich0]

In before the stupid lexus, toyota, mercedes S helpful comments.

[N1rve]

Originally Posted by anthony_12347

So I've got a 2020 M4 Comp with the 20" 666 rims and the standard Pilot Super Sports, and have been looking at some options to reduce the harshness of the setup on some rougher roads.

I don't find the suspension itself too firm on the ZCP, because it's pretty reasonable even over some rougher bumps and potholes, the big bumps aren't the problem. It's the roads that have uneven pavement or rural roads with coarser asphalt that cause a lot of tire noise and harshness/vibration that can get tiring on longer drives.

Wanting to get some feedback on a couple options:
1) Keep the 666 rims, and swap to a Pilot Sport 4S, which seems to be better in the noise/comfort aspect based on a lot of reviews.

2) If the harshness is primarily the 20", drop down to the OEM 19" rim and use the P4S or Contis and benefit from the thicker sidewalls, keeping the 20" setup for track days.

Anyone with a ZCP and 20's done something similar?

Harshness is mostly due to the shorter sidewall of the tire. Even if you get the MPS4s, it's still going to be pretty stiff. People have noted more comfort with 19".

The noise is mostly going to be from the tire compound. You're not going to notice as much difference from MPSS to MPS4S. Road Noise was slightly better on MPS4S but mostly because my MPS4s were brand new. Also, this car doesn't have as much noise insulation due to being racecar.

Try lowering your tire pressure down to 29-30 PSI. I find that has helped a lot. MPG will dip like 1-2.

Also ZCP by default has stiffer suspension for more "performance". Try setting suspension to "COMFORT" instead of "SPORT/SPORT+". Steering doesn't make much of a difference besides weight.

[Darth One]

I agree that PSS and PS4S do not have a very significant difference in NVH

[anthony_12347]

Thanks for the feedback guys!

Totally make sense, and ya I would agree that the short sidewall is likely a big cause. I'll probably start looking into the 19" rims / PS4S combo later in the spring.