Good Morning All

On a set of X-10 Sport Cast Alloy wheels (on an X-Type, to be precise, not on my XK) is there a number stamped or cast that indicates the offset of the rims? On the Jag Wheels Fitment Guide I see in FAQs, I see the car should have 17 X 7.0 wheels. Does the 7.0 refer to the offset? In what form or unit of measure? If the ones I'm staring at have a casting that says in part "17-CH X 52.5 mm" are these the wrong offset? The tires are scuffed badly on the inside edge, and yet the car is in alignment. Any ideas?

 

X Type wheels will not fit I am afraid without adapter spacers, the X Type PCD is a 108mm with a 37-42mm offset and a 63.4 spigot whilst your XK is 120.65 with a 18-20mm offset and a 74.1 spigot


Can be made to fit but a lot of hassle.

 

Hey, Scott, how ya been?

I'm going through this exact same stuff trying to fit wheels (mini-lites) to the MGA.

The first thing I learned is that there seem to be two definitions for offset floating around.
1) Picture the plane midway between the inner and outer flanges of the wheel. If this plane is coincident with the plane of the wheel mounting surface, i.e. where the wheel bolts to the hub, that wheel has zero offset. (This method seems common for non-American cars.)
2) Similar to 1) but the reference plane is the inboard tire mounting surface not the "center" plane as in 1). (An american car - centric friend says this is what he is used to.)

Then there's the question of what's positive, what's negative offset. Here there seems to be agreement: positive offset moves the wheel inboard relative to zero offset.

Units: millimeters seems most common, even when other stuff is expressed in inches.

I have not seen any wheels where the offset is displayed on the wheel itself. Then again, it's not like I've looked at that many.

Hope there's something here of value to you.

Weather improving?

Best,

 

Thanks guys. Guess I should have been a bit more specific. The wheels in question are for my sister's 2002 X-Type. Her winter 16s on steel rims are perfect; her summer 17s on the Sport Alloys are destroyed in one season by having the inside edges carved right down to the belts by something on the underbody. She didn't buy the car new, and we know that the wheels are not the exact same set that were shipped on the car. They match the brochure picture; they LOOK identical, but I suspect that the offset may be too great- the wheels may be for some other car. The local Jag Dealer's service manager is (being) a bit of a knob, and I'm trying to do a bit of troubleshooting ahead of time for Sis.

Mr. J. Jr. is out of storage now, Dennis. New shoes are fitted, top voltage-reduction kit is in place, BCM has been re-programmed, cam-tensioner replacement will take place Wednesday! Summer, here we come.

 

Here's a good explanation of wheel sizing: Wheel sizing - Wikipedia, the free encyclopedia

 

There is a simple check, put a straight edge across the back of the wheel and measure down to the hub face, do the same on the other wheels that clear, you might just need a thin spacer (3mm)

 

Rather than attempting to calculate your present wheel/tire situation, I would be inclined to go to a custom wheel outlet. They will have more measurements and cross reference material at their disposal than you will have time to digest and will probably do the work and calculations for you, including identifying what wheels and tires you presently have and what application/spacing may be required. The custom wheel choices are endless. Unfortunately, because a wheel bolts to the vehicle, many times, little consideration is given to the potential geometry changes that may be occurring, including clearance, steering, braking, etc. Just my two cents.