I reciently drove my XF coupe from Minnesota to Denver. I'll be returning to Minnesota next week but I had one rear Michelin Sport SP with a cut side wall. I found what appears to be the only tire that size in Colorado and installed it was over $400. The 18" front wheels offer no problem finding tires but the rears are another thing. They aren't on anyones shelves. I went to Discount Tire and they located one that someone ordered and didn't buy. My only other option was ordering one and waiting a week. Anyhow, this got me thinking about going with 18" wheels all around to make tire selection easier. With computer controls on just about everything on todays cars it's important to keep tire diameters the same as the original. I thought about buying two original XF 18" front wheels but there's a problem with that. The bolt pattern for front and rear wheels are the same, 5-112mm, but the offset and back space are both different. The front wheels have an offset of 23mm and the rears are 34mm. The front backspace is 5.78 and the rear is 6.61. Ok, using stock front wheels won't work for the rear. After market wheels using the stock demensions for front and rear with front tire size original and 255/40/18 tires on the rear will give the same tire patch on the ground and the exact same diameter/revs per mile as the stock 255/35/19 original setup. For now I'm ok wih my tires but looking down the road switching to 18" all around looks to be a way to reduce costs, keep handling as good as original, make finding tires easier and offer a chance to do some customizing.

Bruce