Speedline Wheels

[GlennH]

Hi Jon,
I have been mulling over your last posting and Mark's reply. You're clearly not having a good time with these wheels and tyres.
A few thoughts have come to mind, perhaps others can add their comments and experiences?

I agree your vibration problem sounds like a wheel balancing issue. Possibly they have been balanced correctly for rotation, but not balanced across the width of the tyre. If they are not balanced across the tyre you can get 'shimmy' which will be felt through the steering. Wide wheels are particularly susceptible to this problem. A quick check for this is to see where the weights have been placed. If they are all stuck on in one place near the rear rim, you may get shimmy. If they are correctly balanced, you should see several sets of weights placed near the rear rim and much closer to the front rim but still on the back of the wheel.

The tramlining is a bit trickier to suggest for. Wider tyres will tramline a bit more than skinny ones, but shouldn't be as bad as you are experiencing. If we assume your steering, suspension, all the bushes, etc . are fine and that the tracking is correct all round, there are a couple of areas to consider.
Firstly, have you tried adjusting the tyre pressures? The lower the pressure, the worse the tramlining will be.
Secondly, the mix of Avons at the front and Toyos at the rear may be the problem. Tyre wall stiffness, compound and tread pattern will all have a significant effect on the way a tyre behaves on the road and will determine the 'slip angle' a tyre exhibits. If the slip angle between front and rear tyres is different, you can get unpleasant handling, if it is greater on the front, it will feel like it is understeering, greater on the back will feel like oversteer, pot holes and steep camber on the road will either have the front pulling away 'downhill', or the rear doing the same depending on which end has the tyres with the higher slip angle. This may explain your troubles when encountering hollows in the road.
If this is the case, the only solution is to match the make and model at each end.

A final thought about the Toyos. I recently fitted GoodYear Eagle F1s to my X-type, replacing the Pirelli P-Zeros that Jaguar fit. Same size, width and profile as the Pirellis. The grip is much improved (especially in the wet) but they tramline much more that the Pirellis ever did and have a tendency to 'kick' sideways when they encounter a pot hole. Higher tyre pressures helped but haven't made them behave as well as the Pirellis in the dry. I mention them because they have a very similar tread pattern to the Toyo's. It may be that the 'Chevron' pattern is inherently more prone to tramlining? Any tyre experts reading this forum care to comment?

Kind regards,
Glenn.

[poprivet]

Many owners of 15" wheels will sooner, or later, be looking for alternatives. What they need is a definitive answer to what wheels will fit the xj-s. Thumbing through a JWM mag from 11/2004 it tantalisingly suggests that most XJ40/XJ300 wheels will fit as well as adapted standard XKR wheels. Now, with more of the modern wheels becoming generally available, especially at the Spares Days etc. what I would like are the exact Jaguar part numbers of the ones that will definately fit!
If some technical guru is reading this how about an article in the JE mag? (after giving us the nod here first of course )
Pop

[Gordon@1962]

I know this may be going off on a tangent slightly but I recently fitted 235/60/15 Pirellis to my XJ-S (Jan91) and now when the car is on full lock rolling down a slope the tyres catch the mudflaps!

The previos tryes were a differnt brand (can't remember which) and I don't remember it doing it then.
Does anyone have any ideas?
My only option maybe to remove the mudflaps?

thanks in advance