I've searched the forum using every combination of words/phrases, but no luck. So, forgive me if it's been addressed.

- Can an '09 XK, with stock wheels accept one size wider tires without rubbing or interference with suspension parts? I've looked underneath and stuck my hand around behind the wheel and it feels like there would be clearance.

I recently bought Bridgestone close-outs from Tire Rack in the stock size of 245/40-19 F, and 275/35-19 R, Any problems with going to 255/35-19's and 285/30-19's? I "up-sized" with one size wider on both my Ferrari and 993 without any issues. But being new to XK ownership, there's lots I don't know yet. I know there would be no issue with one-size wider tires fitting on the stock wheels, it's the clearance I'm concerned with.

Any input and advice are welcomed, and I appreciate the patience with the noob question.
Cheers.

 

Go for it, no problem.
Certainly if without spacers..

I have some doubt on the 315-30-21 as rears I got for my XK..(10,5J ET50)
is going to be more (too?) tight.

 

Should be no problem. I don't think the fronts will rub in full turns. What are the last numbers in the sizes. The ones between 96 and 105....?

 

This tool is helpful for assurance:
https://www.wheel-size.com/calc/

 

21" ??? 315s ????? Do show please..

 

Not ready to show the experiment Steve..
its just for trackday, so no requirements to visual appearance.
Need to customize the wheels still as I could not find a low budget set that fits the XKR 5.0.

 

Drool ...

I was thinking they'd either be Arden or Khan ..and loving the dish

 

TS has his answer, so perhaps I can misuse the tread😉..

Low budget is the challenge for this wheel project 🤣.
I love modern concave wheels but this little project just needs to result in the wide rear Cup2's on the car...
Even the tires are used (not old/worn).

I tried to find 305-25-21 for the rears but could only find new.
And I preferred Cup2 at least at rear to utlize more power and torque in Trac DSC mode.
New Cup2's are at 550€ each...not my ball park for one or two trackday trials.
So the used rears now are 30 sidewalls..

Still looking for front tires to match them.
Front on 9,5J would preferably be Cup2's too, but in 265-30-21..however sticky PS4S would do as well.
Problem is DSC with 6% difference in circumference fwd/rear..
I will check if this can be altered in ECU somehow.
First I will test what happens with the original rear wheels on the forward axle (275-35-19 on 9,5J ET50 instead of ET49, so will fit fine)
​​If DSC goes haywire I will check if there is an option to apply adaptations to the ABS sensor vallues. (I read it somewhere..but now only have icarsoft LR V3..haven't tried yet)



If adaptation is not an option I will put 265-35-21 on the front axle..
Not perfect because will lose 6% brake capacity (more heat)..

This all just for fun, and out of curiousity🤣

 

I use this one most of the time, yours has more useful info for suspension and such but takes more detail to figure out. I'd use mine to start, then verify using your site.
Will They Fit dot Com

 

Thanks @Cee Jay :-). I’m always mucking about with it. Those extra measurement points are useful to me. As you know, “what looks good” frequently doesn’t measure up to “performance improvement”. I like to keep an eye on that as I prefer driving those winding roads.

 

Hey, if you happen to have those measurements handy for suspension and whatnot, would you mind tossing them my way?

 

Classic stance and wheel....;-)
as said, just to get wider rubber on for occasional trackday. (315-30-21 Cup2 on 10,5J ET50)
Needs a little work on fender edge.
Others better use ET 55 or 60 as there still is little room on inside.
Also 25 high tires are close to OEM circumference, but with the 30s I expect to be able to get more power down on the tarmac (5.0R)
Also gives some use to first gear. (Apart from just smoking tires)

 

crap…. I completely missed this from you @Cee Jay .
Yes, I’ll source those measurements tomorrow. Recall mine is the 07.

 

Cool, it'll still give me a good start for the front, and the suspension stuff on the rear will be good, just not the axle dimensions.
Thanks.

 

315/30/21 will run over a 5% difference from OEM tire diameter....did you experience any issues with wheel sensors throwing codes ???

 

Hi Steve thanks,

I haven't tried as I don't have front wheels ready yet.
Also I am still trying to solve a nasty sound from the engine bay..(nightmare)
I believe 5% is the limit for dsc/abs to go haywire.
At least that was the case with my X100R, running 285-35-20 instead of 30s, gave no issues.
But now i've gone wider and higher I expect to be having codes if I run stock front size.
I hope to be able to dump adaptions from ecu and have it have it relearn with the different sizes.
if that is imposible I will choose a front size circumference that is between the bigger rears and the stock fronts. (3% delta)
Probably 275 30 21.
Bigger then stock circumference in front reduces brake system capacity a bit which is not what I am looking for.

 

If you want better traction and more power and better braking, you’ll
have much better results with smaller diameter, wheels, and higher sidewall tyres. I’ve got 305 Cup 2s in the rear with no clearance issues though I reckon anything wider’ll be a challenge.

 

Ive been toying with the idea of running 40 series upfront and 35 series on the rear on my 20s to negate the bone jaring roads around here !

 

With the 5.0R we have too much power and torque🤣.
with larger diameter in the rear it becomes a bit more controlable.
But it reduces brake capacity.
At the rear that is no issue.
But at the front it is an issue on track.

I ran 285 35 20 at rear of the X100R with 255 35 20 in front with no issues at all.

 

How'd the find the the 35 series on the rear ??? Plus I also dislike the look of rubber band profiles as I'm getting older