I have a 2015 Base (no active suspension) with the 18" Vela rims. I'm picking up a set of 20" Gyrodynes for dirt cheap.

For those of you that have upgraded from 18" to 20"...any observations? Improvements? Degradations? This is for both handling, grip and overall ride comfort..

 

I did exactly that swap on my base. Ride comfort is only slightly harsher on rougher pavement, but handling and grip are noticeably improved.

 

How about steering input? My biggest gripe about the 18's is how mushy/sloppy initial steering turn in is.

 

My perception is that turn-in is also noticeably sharper.

 

Mushy? Have you checked the tyre pressures?

On corrugated surfaces there's a difference in ride, but generally I felt ride and handling improved.

It remains over sprung and underdamped - which may be what you call mushy. Try minimising weight transfer changes while cornering.

 

That was my impression when I took delivery of the car. The dampers are very underdamped. I've increased the tire pressures to alleviate some of the mushiness.

 

I noticed tire pressure makes a huge difference in my 20 inch tires. I run 41 psi in front and 43 psi in rears. With the spare tire kit and other weight in trunk. Steering is much crisper with over 40psi. I immediately noticed the difference when the service department dropped it to 36psi. Put the air back up where I had it and all was well. 2014 V8s vert with the active dampers.

 

Wanna sell me your used rims? Will they fit my 99?

 

I'm located in California so are you willing to deal with shipping? And the wheels wont fit. The bolt pattern on the XK is 5x120 and the F Type is 5x108.