I'm thinking of changing my wheels. Wondering if there is a gaget to recalibrate my speedo and mileage if I go higher from my 17"?

 

Of course, if you go to a larger diameter wheel and use a lower profile tire, and the tire diameter is the same as original, no re-calibration is required.

You can visit tirerack.com and check the revs/mile to compare tires.

Devices that you refer to are available for some cars, Don't know if any are available for the XK.

The 20" Wheel option in the XK would seem to require a re-calibrated Speedometer system, maybe a software change.

 

If I do compensate the greater diameter wheel size for the tire size will I get a much stiffer ride? The roads in New Brunswick are really poor, the highways are good but once you get off their poor.

 

As long as you keep the rolling radius within 3% you will be fine, the only time I have every heard of any probs is when somebody tried to fit 24's (bad move)

But click HERE, type in your original size then you can play with various tyre sizes and see what you get.

You will compromise the ride to a certain degree but that is the price you pay for bigger rims.

 

The 20" wheel option is known for a stiffer ride due to the low profile tires used.

We have similarly bad roads in Wisconsin and I find a stiff ride with my 18" wheels (45 ratio tires) let alone a lower profile tire.

The tires provided with the 17" wheels have a 50 ratio.

Other things being equal, Lower profile tires will always provide a stiffer ride.

 

That's what I thought, I feel the same way..my 17" with the 45's is already borderline for me. Maybe I'll stick with the 17" and just get a nicer looking wheel.

Thank You Tony and Paul for your input.

 

I had an R with 18's and now an 8 with 17's. Way better ride and in the real world driving, the handling seems the same.

 

More air (tire width) between the road and the wheel equals less harshness. I'm sticking with the 17's on my XJ8.

 

Thanks guys for all your input and comments. I decided to go with the 18" wheels. I made a mistake on one of my posts I had 245-50-17 not 245-45-17. I'm going with 245-45-18's. My speedo and odometer shouldn't be effected too much, I think there is only about .2 " in diameter difference. So I think my speed will show a wee bit more than what it should be and my odometer will show less than what I've traveled?? I think.

 

The 2000 XKR Factory Fitment is:

255/45/18 9" wide Rear
245/45/18 8" wide Front

You may want to consider using these sizes.

The Odometer reading changes should be negligible.

 

Thanks Paul, I'll order those instead. Much appreciated.