You should probably take your XF to the dealer for some updates to the computer settings.
Changing the diameter of the wheel effectively changes the gearing of the car (since the wheels turn at a different velocity) and will throw off the computers' readings for speed and shift points. Your issues in the rain are likely caused from issues in the differential and maybe the traction control system trying to manage 19 inch wheels using 17 inch wheel calculations. Sometimes you can get away with going up or down an inch in diameter, but two inches creates almost 12% error in the computers' logic.
OK... I'll bite...
The OP means his original post in General Chat: www.jaguarforum.com/showthread.php?t=97443&p=969765#post969765 but in fairness to myself and most other readers that was not in any way obvious.
Originally Posted by holty_40
Originally Posted by longhoya
Sorry, I am probably one of the least knowledgeable members of this forum (my technical field is IT and related topics...) but I do know that when you change the rim you should get a suitably matching tyre and the overall diameter of the wheel does not change. The width of the tyre however most likely did change. I daresay that could affect handling? But gearing not. (I stand to be corrected.)
jbn You are correct
In fact a 19" wheel with the correct 245/40 tyre fitted is in fact 11.7mm smaller in overall diameter than a 17" wheel with the correct 235/55 tyre fitted ( so size doesn't matter )
I have noticed on my 3.0d R sport on a couple of wet road occasions that being a bit quick on the gas can cause a twitch until the TC kicks in. I find it nice to have a little driver feedback and think it is partly due to having an 8 speed auto box. My old V12 E-Type couldn't be taken out in the wet it used to just snake all over the place lol!
Post Thanks / Like - 1 Thanks, 0 Likes, 0 Dislikes
thanked for this post
Still on my Winter Nokians and they have not twitched at all. Cannot say the same about my Summer Goodyear Eagles which do react to a heavy foot.
I really rate the Eagles F1 asymmetric. I have just fitted one to the full sized spare I recently acquired with the intention of replacing the other 4 OE Dunlops when they are due for changing.
Originally Posted by scunny