I was just flippin through the tire rack site and was looking at some potential rear tires . I don't need them yet as I have 10K miles on the Dunlops but I can see they will maybe only last another 5K miles. So I see the thread pattern on the Goodyear F1 tires and it looks pretty interesting. So has anyone used them and if so how do the ride and perform. I also see a minor conflict in tire size where My dunlops are 285/35-20 on the rears but I also see some recommend either 295 's or 300's. So if you use different sizes do you get the speedo changed and is it done through SW.

 

Pirelli 295's are standard on my car with the dynamic pack, Vulcan rims (same as XKR-S). If I have my car long enough I will first replace my stock rears with 300 or 295 Pirelli's. When the fronts go I will change over to a sticker tire like Michelin PSS, Pirelli Corsa, etc. I will try to go 300's in the rear without changing the rotation distance.

 

Suggest you also consider the mich.. PSS tires .. had them on my XKR and going to go with them on the Ftype R...
Anyone that I've met or heard from with a performance car has found the pss tire to be far superior to the Pirelli etc.
A couple of years ago a magazine did a proper test of performance tires and I recall that the pss scored the best .. perhaps there is a recent tire test that will update the findings.
Lawrence.

 

On my 2010 XKR I went with 285 p zero corsa's on the front and 295's on the rear, never been happier with a set of tires. I had Dunlops on as original and they were awful.

I will admit, ever since I was a kid and went for a drive in a countache with Pirelli's on it, I always wanted a set on my car... And they have not disappointed me.

Justin.

 

Deleted. Subsequent posts by Ngarara and jagtoes showed my that my answer was wrong. Rolling radius (circumference) is what counts, not diameter, and that tire width affects rolling radius even if rim diameter and aspect ratio remain unchanged.
.

 

There's a very useful wheel-size calculator here:

Visual Tyre Size Calculator | Kouki Tech

So, for the Vulcans that DGL has, or the Vortexes (Vortices?) that I have, 305/30 tyres only increase the rolling radius over the stock 295/30 by 0.9%.

I'm upgrading to 305/30 Michelin PSS soon, to replace my stock P-Zeros.

 

OK guys I am familiar with tire size so thanks for the response. In the days of old during the days of my engine/transmission transplants I had a lot of fun changing the speedo gears in the transmission based on the need to go to different tire/wheel sizes. In those days there were few if any charts so most of the final gear set was done with gear ratios in the tranny. What I was referring to in my post was I have seen others use tires with the same aspect ratio but the tire size was different. Example my OEM Dunlops are 285/35-20 but I have seen others put on 295/35-20 or 300/35-20 and even 305/35-20. All of these tires have different circumference so the speedo would read differently. I know on my GMC pick up the dealer can change the tire size in the SW to compensate for different OD's. Just wonder if Jag can do the same.

 

Even if the speedo is dead-on accurate with brand new tires, it will become slightly less accurate as those tires wear. GPS nav speed stays accurate.

 

Yep , gotta and yeah a 2 or 3% error isn't a problem. I suspect a GPS would be better but I don't think everyone has one. Well maybe just me but I'm one of those flip phone hold outs , lol. By the way is the 19" rim/tire the same as the 20" rim/tire. I don't know the tire size for the 19". Do I assume the circumference is the same?
PS , I'm just making conversation here as we got 4-5" of new snow last night and I'm to lazy to go out and shovel and plow. HAHAHAHA

 

Switching from 285/35/ZR20 to 305/35/ZR20 will give a 2%-low speedo error (i.e. you're going 2% faster than the speedo says). Since the speedo reads about 2% high anyway, it would pretty much balance out. Jag's approach is: only use the standard tyre sizes, so I don't think you'll get any joy there.

 

It appears the standard fit for 19" rims is 245/40ZR19 front, 275/35ZR19 rear. That is 4.6% less in rear circumference; presumably if you changed wheels, a Jag dealer would change settings using the diagnostic tool (allowed because it's a standard wheel/tyre combination).