XJR - Overtyred ?
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From: Peregian Springs Qld 4573
XJR - Overtyred ?
Most tyre/rim charts indicate that with the 8" rims of the XJR the minumum width tyre is 215, the ideal 225 to 235 and the maximum 245.
So why has Jaguar fitted & stipulated 255/45 as the original & replacement size for the XJR.
Most sources indicate that the major cause of tramlining is the tyres.
Previous threads indicate this problem can alleviated with the narrower tyre size. ie. 225/50 or 235/50. Neither size deviate much from the original 255/45 other than for tread width.
Less tread width with little or no tramlining appears an obvious choice as regards safety & steering feel.
John Herbert
(1996 Jaguar XJR)
So why has Jaguar fitted & stipulated 255/45 as the original & replacement size for the XJR.
Most sources indicate that the major cause of tramlining is the tyres.
Previous threads indicate this problem can alleviated with the narrower tyre size. ie. 225/50 or 235/50. Neither size deviate much from the original 255/45 other than for tread width.
Less tread width with little or no tramlining appears an obvious choice as regards safety & steering feel.
John Herbert
(1996 Jaguar XJR)
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From: Pacific Northwest USA
The 8" rim width, though perhaps slightly narrower than some tire manufacturers would suggest, is not seriously deficient, IMO.
The original tire was the P-Zero. I suspect Jaguar consulted with Pirelli and the 8" rim was deemed appropriate for *that* tire at *that* time. This would have been during the XJR development stage, circa 1993-94?
Most sources indicate that the major cause of tramlining is the tyres.
Previous threads indicate this problem can alleviated with the narrower tyre size. ie. 225/50 or 235/50. Neither size deviate much from the original 255/45 other than for tread width.
Less tread width with little or no tramlining appears an obvious choice as regards safety & steering feel.
Previous threads indicate this problem can alleviated with the narrower tyre size. ie. 225/50 or 235/50. Neither size deviate much from the original 255/45 other than for tread width.
Less tread width with little or no tramlining appears an obvious choice as regards safety & steering feel.
Narrower tires certainly made all the (positive) difference in the world in my XJR/6.
Cheers
DD
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From: Sanford, NC
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From: Scotland
John,
You make a very interesting point. The sales literature for the XJR brags about the tyres being specially developed for the car, and since we know that the Pzero tyre was not unique to Jaguar, I assume any factual accuracy attaching to the boast is based on the tyre size being unique to Jaguar. In any event, I think it is fair to say that the tyres didnt arrive on the car by accident, and did represent an attempt at rocket science at the time. Bear in mind that 17" wheels were the largest ever fitted to a Jaguar!
The tramlining debate is well covered in other threads, so I will not attempt to rekindle it, beyond observing that my X300 XJR does not particularly suffer from tramlining on factory spec tyres, nor did it when new.
You make a very interesting point. The sales literature for the XJR brags about the tyres being specially developed for the car, and since we know that the Pzero tyre was not unique to Jaguar, I assume any factual accuracy attaching to the boast is based on the tyre size being unique to Jaguar. In any event, I think it is fair to say that the tyres didnt arrive on the car by accident, and did represent an attempt at rocket science at the time. Bear in mind that 17" wheels were the largest ever fitted to a Jaguar!
The tramlining debate is well covered in other threads, so I will not attempt to rekindle it, beyond observing that my X300 XJR does not particularly suffer from tramlining on factory spec tyres, nor did it when new.