Hiya all, what difference would 18" rims make on an S with OEM factory rims? I'm dismayed that my 4 y.o. michelins(not a fan of Mich's) have flat spots that seems to be lingering even after 300 miles so they seem here to stay. If I'm buying new Conti's (a big fan of DW), why not go w/18s that look better, tighter sidewall and maybe how much worse a ride?

Any one else already go this route from 17" to 18"?

 

What model/year is the car?

Going up to 18"s would only effect the ride (lower sidewall less cushion), as you said and might change your speedo readings.

Use a tire calculator to find the nearest rolling distance and keep things correct.

The problems with the S-Type is going the other way since brake rotor clearance can become a problem with smaller wheels.

But if you want the easy path to 18"s look for a set of wheels from an XF. That was what I did when I had to replace the set of wheels that my car came with.
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Jaguar: Grace, Pace, and Space - Sir William Lyons
Current Hers: '13 Lexus ES350
Current Mine: '08 Jaguar S-Type 4.2 "Satin Edition" (250.06 whp / 259.67 torque)
Past Ours: '05 X-Type 3.0/auto Jaguar Racing Green

 

Should be even easier to get S-Type 18" rims (far more scrapped S-Types than XFs) - but as above the ride will be harsher.

Flat spots are the tyre, really. Leaving a car standing a long time can cause them, too, especially with low/medium pressures.

What tyre pressure are you using and yes we need car details!

 

Yes, my new-2-me S type. And good call on the XF 18s! Thnx! And I know the formula by heart- widthXratioX2div by 25.4+rim size in inches=26.25" height overall on the OEM 17"

OEM 18s are 245/40/18 so + 25.71 so slightly shorter in diam and height. 255mm wide 18's would come close to oem 17s.

And my car sat for 18 months or so in Miami heat w/original 92 y.o. owners-not too hopeful they'll make a comeback and tire shaving is a lost art in this area.