My x type has 17" low-profile tires. The rid is rather bumpy with these ties and I've been thinking about going with a standard "balloon tire or high profile. Would I need to get new wheel rims - say a 15", or can I fit a high profile tire to the 17" ones that are already on the car. After all is said and done, will I get a smoother ride? What's the point of the low-profile tire anyway? Thanks for any help!

 

15" or 16" would certainly give you a cushier ride. I would suggest going to tirerack and checking out tire options. You can identify your car and let them identify suitable tires in various sizes. Any tire with the same diameter as you current tire will work, the profile will simply be taller for the smaller sized wheels.
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Jaguar: Grace, Pace, and Space - Sir William Lyons

 

Different tires might help - I have 225/40/18's and went from a very stiff summer performance tire (Toyo Proxes 4) that cornered very well, but gave a somewhat harsh ride. Just recently I changed to a performance all-season tire (Continental Extreme Contact DWS). I gave up some cornering grip vs. the Toyo, but gained a much nicer ride quality on the highway - a compromise I'm very happy with. The ride quality of the Continental is as comfortable as the 205/55/16's that my X came with.

 

Hi Pab...The front end of my x type rattles and cluncks like the dickens! And the ride is rough with the 17" low-profile tires. Where do I begin to try and smooth out the ride and eliminate the noise?

 

>The front end of my x type rattles and cluncks like the dickens

I'd say your problems extend beyond rough ride from low profile tires...

You should do a comprehensive check of your front suspension, you may have worn ball joints, or strut bushings, or some other problem.

I'd suggest taking it to an alignment shop and letting the tech have a look.
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Jaguar: Grace, Pace, and Space - Sir William Lyons