My dealer can get me a 2017 XJL with awd. He found me one but the wheels are 20" and not the 19" ones I wanted. He said they can put on the 19" ones off a car they have in stk and take off the 20".

I asked him 'won't that make a diff in the speedometer readings?" And he said 'no', that the dia of the wheel/tire assys would be the same.

His answer troubles me because I was sure the reading would be off if 19" were put on instead of 20".

What do ya'll think?

 

You need to find out the tire sizes and then find out the OD's. Then compare how far off they are.

The dealer may be right?
.
.
.

 

The tech can hook up the SDD and go into the tires and wheels area and set it to your tires.

 

Thanks for both answers above. It seems the dealer is most likely right then. Especially if the SDD can do the correction.

 

Nice little app here: -

https://tiresize.com/tyre-size-calculator/

Enter in the two tyre sizes and it'll tell you the difference in diameter, and the speedo difference. In my case, I have downsized from 19" to 17" a whole two inches, yet very little difference in speedo reading.

 

OK, FRASER MITCHELL, the site you led me to shows the dia is the same for the 19" and 20". So the dealer was correct and all will be well at the end of the week, give or take a day.

I guess I'm not a Fleet Manager since I've only four: '14 CL550.....'07XK.....'14 PANAMERA SE HYBRID.......ML350 BLUETEC. One two many in my mind. Ones got to go. Panamera is to be traded and then one more to sell off.