So... mainly this is wife's car. She loves it. I just primp and tinker...heheh... but she has a slow leak on left front tire. Not a huge deal. Every 4 or 5 days I fire up compressor and add air, BUT....

So the tires are brand new. The dealer must have put them on before we bought the car. 17 inch wheels. It appears the offset is 52mm. Her wheels have a fair amount of "curb rash" and I wouldn't be against getting her some new wheels if this is anything worse than just a bead leak or something. But I'm wondering just how far I can stray from that 52mm offset.

And... trying to understand the offset..... if I were to get a wheel with 42mm offset... does that put the wheel (and tire) 10mm more towards the outside of the wheel well? Or does it move it all inboard?

 

yardbird, offset is a measure of the distance between the center of the rim and where the hub sets on the rim. A positive number means that the hub area is more towards the outside of the car than the center of the rim. So, by going to a lower (positive still) offset, that will move the whole tire towards the outside edge of the car. If you stick with the stock width tires, you should be fine. If you start going with a wider tire, you can start to run into issues.

When I had my X-type, I had the stock 17" rims and was able to go up 1 size in width while keeping everything else the same on the tires. This resulted in a very mild rub of the tires on the fender liner under the worst case conditions.

 

I would pretty much be staying with the stock tire size. Just really considering new wheels. Nothing outlandish. I actually like her stock wheels. They're just beat up. And stock ones are crazy expensive.

Looking at something like THIS

Maybe not ending up on that one exactly, but it's very close to the stock LOOK and only 4mm less backset.

Make sense?
Am I thinking this right? heheh

EDIT **
And that link comes up with vehicle listed as Volvo for some reason, but I'm on the page and it's for 2006 Jaguar X-Type VDP.
Wheel is 17x8 where stock is 17x7.5 I think. And offset 48 instead of the stock 52.5mm

 

You need to look at it like this (if I can type it as well as think it haha) ...

If it's 7.5 with 52mm and your new ones are 8 inch with a 48 that means the outside wheel lip will be pushed outward by 10mm and this is why...

Imagine if the 8 inch wheel had the same 52mm offset, that would automatically make the wheel lip be further out from the centerline of the wheel by 6mm on either side. Then add in the 4mm negative difference, which pushes the wheel outward, to get down to 48mm and that makes the outside of the wheel stick out 10mm more and 2mm less inside clearance. that 12mm total difference makes up the 12mm increase (1/2 inch) in overall width.

Let me know if I confused the hell out of you lol

 

Yardbird, X-TypeMentality has it right on the head with the direction and added room the tires are going to take up. This will also "square up" the tire some since with the 7.5" wide rims the bead of the tire is normally pulled in some compared to the width of the tread where when you use the 8" wide rims, the bead is going to be more inline with the edge of the tread, giving the tire a more square look.

 

eeeerrrrrgh........ maths......

I don't think 2mm inboard will ever be a problem. The 10mm outboard.... is a hair over 3/8 of an inch... I don't see a problem there (just went out and looked) but I think I'll look for something similar in 7.5 width and correct backset. The options there are pretty limited.

AAaaand.... just found THIS calculator showing the effects of different wheel sizes and offset

If I find a 7.5 with 48mm backset, I'm still pushing it all outboard by 4.5mm

I appreciate the explanation. Now I can at least juggle numbers and have an idea what I'm juggling.