Dramatic change with just wheels/tires? Unexpected

[belcom]

My Z had a set of 18" RTX Envy wheels, with Conti SSR RFTs from previous owner, both front and rear rims were same size and offset (8in and 38mm offset) but fitted with different tires 225 front and 245 rear. I had stock sport suspension but shocks were basically completely shot.

Ride was kind of terrible which was kind of fixed by a new set of ST X coilovers and handing has improved a lot however it still did not feel right. It was pretty stiff and lets say I had to tighten my abs every time I hit something on the road. It was almost a reflex. Again it was decent but something was off.

Suspension felt jittery, had quite a bit of bump steer, front end felt loose and tram-lining was bad, after going over small bumps at speed car felt unstable and overall just felt it was too stiff. Felt like tires leave the asphalt at times. For some time I thought ok, new suspension plus this particular chassis it must be the way it is.

So yesterday, I picked up a set of 19" Style 225 OEM wheels with Bridgestone Potenza 050A RFTs. 225/255. Put them on right away and drove for an hour over different surfaces and at different speeds.

First thing I had noticed even though these tires are also RFTs and essentially what people call rubber bands is that the ride was smoother, I felt that the wheels don't hop and keep their contact with the tarmac way better. Bumps are now absorbed much more smoother too without losing balance, chassis lateral movements started to feel normal, bump steer was pretty much gone, steering now feels great, front end stays planted, tram-lining is gone. Directional stability and lane changes are now much more stable. It feels awesome now. How it should be. And its not even height adjusted properly yet, nor aligned, nor corner balanced.

Previous wheels were a bit bent and had some vibes, plus I didn't like grey too much and I thought the tires sizes were not exactly a good match. So that's what I wanted to fix however got a MUCH more pleasant surprise in the way Z feels overall. I just basically fell in love with it once again but now in a different way.

Unbelievable how much just a set of proper wheels has changed. Thoughts? Why would it have so much effect on pretty much everything handling and chassis related. I am a bit puzzled to be honest.


https://www.zpost.com/forums/showpos...postcount=2156

[Finnegan]

Perplexing. Going 18" to 19" usually reduces ride quality. All I can think of is: 1.) the RFT design is just that much better with those Bridgestones; 2. The old wheels were heavier than the new wheels. Get an alignment and it should be even better! Maybe just enjoy it and call it a day .

[belcom]

Originally Posted by Finnegan

Perplexing. Going 18" to 19" usually reduces ride quality. All I can think of is: 1.) the RFT design is just that much better with those Bridgestones; 2. The old wheels were heavier than the new wheels. Get an alignment and it should be even better! Maybe just enjoy it and call it a day .

My sentiments exactly. I am thinking the same, Bridgestones are that much better plus new wheels are slightly lighter. Although, the 225s are far from light (12.63kg or 27.8lbs).

Actually, I will put the old wheels on the scale for comparison while I still have them and then also weight the 225s. Really curious what the difference is.

I just went for a lengthy drive last night and the ride is so excellent now. ST X coil-overs feel awesome.

Love the Z