I like the look of wider tires on my Jag. I currently have P225 60/R15 tires on my 1988 XJ6 Vanden Plas. Will P225 70/R15 tires appear as wide, or will I have to go with P235 70R15 tires to maintain the same wide look as the 60/R15 tires? Also, can I potentially cause suspension or axle problems by using P235 70 R/15 tires?
The reason I am considering 70/R15 tires is because my speedometer is reading six mph faster than actual and I believe it is because the circumference of the 60/R15 tire is smaller which results in faster revolutions.
So if you put a larger tire on, one complete turn of the axle is still going to cause the tire to make a complete revolution; and that complete turn is going to give you more distance covered along the ground. Thus, your speedo will read a lower speed than you are actually traveling.
Reference https://www.physicsforums.com/threads/wheel-size-and-speed-help.3071/
Yes. The recommended tire for my car is P205 70 R/15. So the 70 R/15 should get the speedometer accurate.
Although specs vary a bit by manufacturer here’s what you’re dealing with
205/70x15 26.5" diameter
215/70x15 26.9"
225/70x15 27.4"
235/70x15 28.0"
225/60x15 25.6"
The Series III XJ6 was built with both 205/70 and 215/70 with no change in speedometer calibration…Jaguar apparently felt the readings would be close enough
Anyhow…
The most accurate reading would come by staying in the 26.5" -26.9" range. The shorter tire, such as your 225/60 size, make the speedo read too fast, as you observed. The 225/70 and 235/70 will make it read too slow. Choose your poison
You might try a 235/60x15, which is 26.1" diameter. Hard to find that size, though. Wide look, fairly close speedo reading. BUT…a 235 tire is a bit too wide for your 6" wide wheels. It’s really meant to be mounted on a 7"-8" wide wheel to work properly.
You shouldn’t have any suspension problems with any of these sizes.
As for the wide look, a 225/70 would be the same section width as a 225/60; a 235/70 the same section width as a 235/60, etc. The lower profile, and differences in tread design and shoulder shape, can make one look wider than the other.
Cheers
DD
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Thanks D. D. Good information.
That’s the truth! And too wide for 6 1/2 or even 7 inch wheels too, as were factory spec on the XJ40–which might be what the OP has? IMHO.
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There is indeed some concern about suspension with really skinny tyres - apart from stumpy ride it increases suspension shocks. Part of the tyres job is to soften suspension loads - but if you can stand the ride the suspension can; ‘60/70’ is not that skinny…
The speedo reading is more a matter of mental adjustment…
Frank
xj6 85 Sov Europe (UK/NZ)
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I’d second Bob. The car on the icon is what an 88 XJ6 would be expected to be: an XJ40. As such the car was designed to ride on different tires anyhow - metric Michelin TRX. Thus all analogies to our series Jags tire size combos are questionable.
If you want wider tires, you might look at what Jaguar, Jaguar Sport and or Tom Walkingshaw, in Germany Arden, did on later or faster cars, and get original rims to fill the bigger shoes … Good luck and I’m looking forward to see the outcome!
Jochen
I think the P225 70/R15 is what I wii go with. It will give me the wide look I desire, and a bit more height. The speedo reading will just have to be off a bit…no big deal.
Any recommendations for good looking P225 70/R15 tires?
To my eye, even the 215/70 over fill the wheel wells and look like big balloons. I’m running 215/65 tires and they give a nice stance and have a wider look than the 205’s. I have 225/70’s on my old SUV and they are a TALL tire.
Hummph! Now I am thinking maybe that’s why I have P225/60’s on the car…the 225/70’s looked too tall. The jag in the above photo looks good…I am assuming those are 215/65’s…certainly a size I will consider.
Here’s what she looks like.
Out of interest 215/70R15 tyres that were fitted onto the V12 cars are generally speaking lots of money, because they are generally fitted onto fantastic cars that have V12 engines, not just from Jaguar but from Ferrari and Lamborghini. Pirelli recently made this tyre again http://www.longstonetyres.co.uk/page/215-70vr15-pirelli-cn12.html it is the original equipment for the SV version of the Muira, and for now represents a massive bargain for you chaps.
Read the page carefully and make your own mind up, but I don’t think you can get better value.
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XJ6 cars tended to fit 205/70VR15 tyres. I think the series 3 moved onto the Pirelli P4000. (incidentally we took some off yesterday with the date code of 2008 which i think was the last batch they made. They aren’t making the P4000 at present, but Pirelli do make a Cinturato in that size http://www.longstonetyres.co.uk/page/205-70-r-15-pirelli-cinturato-cn12.html it probably is the best value tyre in the size