I need snow tires on my 04 XJR (yes, I drive it year round). I just found a nice used set right by my house, and if they fit it I would save myself $1200 over new ones!
My stock tires are 235/55R20, and the snows are 245/45R20. I called tirerack and they figured I would add 3/4 inch to the total diameter with the 245s. I am sure the rears would be fine, but will I have clearance issues up front? I can't imagine 3/4" would make a huge difference...
Please advise!!

 

I do not if they will fit but here is a tyre size calculator that gives the tyre size differences by comparison.

Discounttire tire comparison calculator

For instance my tyres should be 235/50 R18 and it has fitted 245/45 R18. They run fine and fit fine with no rubbing anywhere on all locks. Although I will change them back to original spec once they are worn out, that's just my OCD.

 

You need to reprogram the wheel size to the car so the speedo will work correctly. Jaguar offered a variety of wheel sizes on these cars over the years from 17" all the way to 20". Just look inside the fuel filler cap for the tyre pressures, you'll see quite a variety of sizes there.

 

I ran 255/35/20 on mine with no issues.... Currently running 245-45-18..... You cannot exceed 28.125 inches total diameter without striking...

 

Are you sure about that ? I find that the speedo reads about 4mph high at 70mph, but that the odometer agrees very well (<1% error) over routes as plotted on Googlemap. I rather assumed that it the odo is calibrated from the sat nav, and the speedo over-reads because manufacturers always do that to avoid any comeback if people get booked for speeding.

 

As long as it is not more than 2% change in tire size, speedo does not need to be recalibrated... Once you hit 3%, you are screwed!

 

It's not wheel size that matters for speedo calibration, it's tire O/D.