The stock tires are 255/35 in the front, and 285/30 in the rear.

 

Yeah, the fronts are 40 and the rears are 35 on the XJ's. I had 30 rears on a Maserati QP Sport GT before I got the XJ and was forever dinging the rims in potholes.

 

Interesting. I didn't realize they used different tires on the different models. What width do they use, and what brand tire?

 

It's worth noting for those that might not know that profile is just a ratio of sidewall height to tread width, with the two different profiles on these tire sizes actually having the same sidewall height. Go wider still and a 25 profile will have the same sidewall height also.

Bruce

 

Thanks Bruce. That's why I asked what the width of HouTex's tires are. Since they're mounted on OEM 20" rims, I was wondering how it was that he has a 40 and a 35.

 

The rear on the XJ is a 275/35, so the height of the tire is 96.25 MM vs. the rear on the XK of 285/30 with a height of 85.50 MM. This is about a 1/2" difference, which doesn't seem like much, but I had 285/30's on my Maserati QP and damaged the wheels frequently by bottoming out in potholes. Just have to be careful.

 

I'll be revealing my ignorance once again, but I have to ask another question. The XK I have on order has a choice of 19" or 20" wheels.

The set up on the 19" Caravela wheels is 8.5" 245/40 ZR 19" front, and 9.5" 275/35 ZR 19" rear.

The set up on the 20" Kasuga wheels is 9" 255/35 ZR 20" front, and 10" 285/30 ZR 20" rear.

What I've learned in this forum is that a tire on a 20" wheel is going to have 1/2 inch less rubber between the road and the rim. However, it seems that what you're saying is that you can get that 1/2 back by buying a tire that isn't as wide, yet will still fit on a 20" rim.

Am I correct in that understanding? If so, then what's the trade off in getting a tire that is not as wide? A 275/35 tire is 10.8267 inches wide. A 285/30 tire is 11.22 inches wide. Thanks!

 

Michael...you have to find out the width of the rim to see what the limits of tire size would be.

Stop knocking yourself out. The car rides great on 20's, go drive one so equipped if you haven't already and you'll see.

 

For the same aspect ratio, a narrower tire will give you less rubber between the road and the rim, not more. That's why the aspect ratio is usually bigger on a narrower tire.

 

Right. You have a higher aspect ratio, and a narrower tire. I just don't know how narrow of a tire you could go on a 20" rim that's 9" wide in the front, and 10" wide in the rear.

Essentially, in order to get the 1/2 inch extra in height, you're giving up 1/2 inch in width.

So, my question was asking what are the consequences of giving up that 1/2 inch in width?

 

Can't tell if you're confused...but let's start here...

-the 19" wheel can only use the 245f and 275r tire sizes you mentioned in order that their overall diameters are the right size for the car.

-the 20" wheel can only use the 255f and 285r tire sizes you mentioned in order that their overall diameters are the right size for the car. Their sidewall heights will be about 1/2 inch less than the 19" tires, so 1/2" less to absorb damage from pot holes.

-The 20" tires have about 1/2" wider tire tread, but won't really have any practical difference in grip. Your decision can therefore be based on what size you prefer visually, and the wheel design you prefer. If you end up preferring the look of the 20's just realize that there is a slightly better chance of damaging that size wheel do to less sidewall to protect them, the tires are slightly more expensive, and they may ride not quite as smoothly (but certainly still quite acceptable...you can test yourself to confirm).

Hope that helps,

Bruce

 

Yeah, I got confused because HouTex has a 20" wheel that he says has a tire that is 275/35 on the rear.

But maybe he can get away with that because it's on an XJ, instead of on an XK??

 

Probably his stock size, but either way it doesn't matter in the least, or affect what you need for your XK. You only have two choices...19" or 20", and it will come with the correct tire sized noted for the XK.

Bruce

 

I don't know what range of tire widths will fit on the 20" Kasuga wheels that I have on my XJ. I only know that the fronts are 245/40 and the rears are 275/35. If your dealer is going to sell you a set of Kasugas for your new XK with the wider tires, then I guess they feel it will work.

By the way, you asked what brand of tires I have--they are Dunlop Sport Maxx GT's and I am very pleased with them. They have very good grip and I got 18,000 miles out of the rears and will probably get 22,000 out of the fronts (and I drive pretty agressively). The rears were almost $400 each.

 

I asked the dealer about the different tire sizes today. He said that even though it's the same wheel, the difference in tire size is because the XJ sits higher than the XX.

 

I have a 2013 XKR with 19" Tamana wheels. I want to move to 20" wheels - but I would prefer the 20"x9" fronts and 20"x10" rears like the XKR-S has - so that I can get 255/35-20 on the front and 295/35-20 on the back. I can find Kasuga, Nevis or Osaro(sp?) in that spec. But will the 9", 10" (front back fit?). It appears that the XKR's shipped with 8.5", 9.5" 20" originally. Any help?
Thanks

 

My XKR 75 has the same rim size & tyres as the R-S, and there are no clearance issues. In fact, you can go to 305/30 on the 10.5" rear and 265/35 on the 9" front without any issues, provided you haven't lowered the car. The only rims in those widths, as far as I know, are the Vortex and Vulcan.

 

Ref the tires:

I have 20" rims which were standard on the 2009 XKR Portfolio Edition.

Tires sizes are 255 front and 285 rear for a 8.5" front and 10" rear rim. You can see photos of my rims from the photos in my signature.

As far as the car goes, I would CANCEL the order. While the dealer states that at $81,000 it is a good deal, the 2013 XK will suffer tremendous depreciation within the first 24 months. I would estimate after 18 to 24 months the car will be worth about $55,000 to $60,000. It's only an XK, not an XKR.

If you were patient you could find a beautiful low mileage XKR or XKR-S for about the same as what you are spending. There has been deep discussion here on these forums about the massive depreciation that these cars suffer within the first 24 to 36 months.

Complete some due diligence and you will soon find out the depreciation of these Jaguars are quite deep. If you can financially handle the depreciation factor of this car then go with it. It sounds like you are a bargain hunter, so why suffer 2 to 3 years out with a car that will be worth 30 to 40% less.

Spend your $81,000 wisely, get an XKR or even a XKR-S....these premium cars can be found in like new condition, low mileage and still under COP warranty program.

I certainly don't want to bust your bubble or excitement about a ordering a new 2013 Jaguar XK, but you have to face reality and realize what is ahead as far as depreciation. Considering it's a 2013, and this is 2014, it is already one year old. Once you drive it off the dealers lot it's probably worth $68,000.

Update: I did not realize that this thread was started back in April 2012.....so I suspect the car is now valued at about my projected value of $68,000 mayber less.

 

I'm partial to the 20" Kalimnos. I purchased my car used with the Caravela which could be a full time job to clean if I didn't immediately change my pads to Ceramics. Regardless of the rims you get, consider going to ceramics or your car will be covered with brake dust, not only on the wheels, but it gets onto the fenders as well. Good luck with your ride.

 

Mine has the Kalimnos wheels (I think). I don't have any problems cleaning mine, or any of our cars because I use a gurney for the wheels (you shouldn't use it on the paint while the car is newish, until the paint hardens). It was only $150 or so, and saves a lot of pain, the wheels take seconds to clean, and it is pretty handy for other stuff around the house as well. 2 thumbs up for that.