Speedline Wheels

[Jon]

Hi

I've already posted this on the JEC messageboard, so please don't bother to reply on both as I'll check them both

I've recently purchased a set of 16" x 8J 'Speedline' wheels for my '87 XJ-S. They are a different offset front to back (smaller offset at the front which will have the effect of making the wheels stand further out)

Now, I've seen some articles suggesting that different tyre sizes were fitted on the front and back wheels of these tyres, and that its necessary to fit 'lock stops' on the steering rack to avoid the front wheels fouling the arches. However I've had a glance at my existing wheel / tyre arrangement (215/70/15 on 'starfish' wheels) and there seems to be bags of room, I'm planning on fitting 235 width to the speedlines. Will I get away with this or will I need the 'lock stops'? Or were the different offset wheels brought in to make this no longer necessary?

Thanks in Advance

Jon the XJ-S boy racer.

[GlennH]

Hi Jon,

I may be wrong in this, but I think the 8J x 16 Speedlines with the different offsets were only used on the XJR-S cars. The ones on the XJR had a different offset again (22mm?) but the same on the front and back. I believe part of reason for the 19mm front offset was to help with clearance for the steering. The 33mm offset on the rears gives just enough clearance between tyre and wing and as wide a stance as possible.
The correct tyres for a XJR-S on these wheels are 225/50 R16 on the front and 245/55 R16 on the rear. 235/60 R16 will give you about the same diameter so your speedo will be within about 1%.
Not sure what tyres are available in 235/60 R16 size, but 245/55/ R16 are very thin on the ground. I have only found Pirelli P6000s and Toyo T1-Rs in this size. I've just gone for the Pirellis.
Hope this helps,
Glenn.

[Jon]

Hi Glenn,

Thanks for the prompt reply.
Do you believe the front tyres are narrower and shorter for clearance reasons? Ideally I'd like 245/55 on the back, but I'm thinking 235/60 due to the scarcity (and expense) of the 245's, as you've already mentioned.

[GlennH]

Hi Jon,
I'm afraid I can't give you a definitive answer to your question, but I just looked up the detailed specs for my XJR-S and found that it uses the sportspack steering rack with 12mm lockstops. It doesn't say whether this to ensure clearance for the wheel rims or the tyres.
It may be worth a search on the forums on the Jag-lovers website to see if anyone there has tried these wheels and larger tyres on their car. It's likely that some of the guys racing their XJ-Ss will have gone larger and wider.
Regards,
Glenn.

[HerefordMark]

The lower profile on the front tyres is to make the car turn in better - see the LJK Setright review of the XJRS in the Brooklands Gold portfolio. As for the rears, they are hard to find, but I have the Toyo T1-S on mine and they are excellent. Expensive, yes, but with a limited mileage policy, they'll last a few years.

[skodajag]

Hi - can anyone clarify what the different offsets were for the XJR-S, using the 16inch Speedline alloys? Also does anyone know if the Speedlines on the XJS's produced by TWR prior to Jaguar Sport and the XJR-S also had different offsets front to rear?
Thanks
Jonathan

[GlennH]

Hi Jonathan,
For the 16" speedlines on the XJR-S :- 19mm offset front and 33mm offset rear.
I believe the TWR cars prior to 1989 (when the Jaguarsport cars came out) used 15" speedlines. I don't know what offsets were used.
Regards,
Glenn.

[skodajag]

Thanks Glenn, that's helpful. I have a brochure for TWR prior to Jaguar Sport and it shows that they offered both 15 and 16inch Speedlines. Does anyone know if either or both of these had differing offsets?
Jonathan

[Jon]

I'll probably be in a better position to recommend this outfit when the tyres come, but I've just invested in a pair of rear tyres for my shiny speedlines at what seemed a favourable price: -

http://www.camskill.co.uk/products.php?plid=m4b0s294p0

[Jon]

Sorry to drag this topic up again - but it seems my shiny speedline wheels arent going to fit, at least not the 245 / 55 /R16 Toyo's I have on the back.

They will foul the arches, I've checked this by jacking the wheel up into the arch.

I can only conclude from this that either TWR cars have much reduced suspension travel, or the wheel arches are rolled out. Can anyone confirm this?

Anyhoo, seems I now have two options, sell the back tyres and get some skinnier ones, or just spit my dummy out altogether and sell the entire set.

So, if anyone is interested in a pair of toyo T1-S tyres 245/55/16 (brand new) or an entire set of 4 refurbished speedline wheels with all brand new tyres (225/50/16 Avon ZZ3 on the front) then message me! I'm in the Nottingham area.

[GlennH]

Hello Jon,
From everything I have read about the TWR cars and the XJR-S in particular, no changes were made to the wheel arches or wings. They are all standard parts from a V12 XJ-S. The rear suspension was changed to use shorter, higher rated springs and special Bilstein dampers which lowered the normal ride height, but didn't affect the minimum height. That is the same once the coils are bound and the hubs on the bump stops. The rear tyre clearance is very tight on my XJR-S, less than 1/3rd inch between tyre wall and wing, but the tyres don't foul the body at any suspension height.
To address your problem specifically, are you sure the tyres will actually touch the wheelarches, or do they just look to be very close? If they will, is the problem the same on both sides of the car? Has the car ever suffered damage to either rear wing? Have you verified the tyre centre fitted the 245s to the 33mm offset wheels?
If all of this checks out, could the Toyos be a bit wider than expected?
Do they measure exactly 245mm across the tread?
Sorry to pose such obvious questions, but it's sometimes easy to miss the obvious. Been there, done that too many times.
Regards,
Glenn.

[Jon]

Hi Glenn,

Thanks very much (again) for those suggestions.

Yesterday I had offered the wheel up on the nearside, but your suggestion about accident repairs had me thinking, I am aware of some repair on that wing.

Today I offered a wheel up to the nearside and backed it up the ramp, hey presto, about 1/3 inch clearance. The same test on the other side results in virtually 0 clearance, so it looks like its a trip to the bodyshop for some remedial action!

As there were no signs of contact or horrible noises on the nearside, though, I've opted to fit them, and I'll have a word with the bodyshop this week. They look the business!

Just one final question to pick your brains with, do you know the recommended tyre pressures?

Many Thanks

Jon

[GlennH]

Hi Jon,

I'm glad to have been of help. Happy too that you found the problem.

The Speedlines do look really good and the wide rears should give you a lot of grip the back.

You might have to experiment a bit with tyre pressures.
On the V12 XJR-S they should be 35psi front and 32psi rear. The kerb weight for this car is 1800Kg. I suspect your manual 3.6 is going to be a bit lighter so you may get better grip if you drop the pressures a bit.

My handbook says that 'maximum comfort' can be achieved by dropping the pressures to 29psi front and 22psi rear (yep, it really says 22psi). I tried it for a few days but can't recommend it. The handling was 'orrible - It felt like the back was running on a couple of jellies

Let us know what you think of the Toyos. I was torn between them and the Pirellis I eventually settled on. Also, have you had to fit lock stops on the steering rack?
Cheers,
Glenn.

[Jon]

Bah, more problems! I don't know if this wheel profile doesn't like the std. suspension set up, but the wheels have induced a large tendency to 'tramline' and at low speeds in particular I seem to be always fighting the car to keep it straight if it goes into a hollow... I've fitted larger wheels / tyres to other cars and not had this problem before, is it just to be expected?

Also, between about 70-90 mph there is an unpleasant shaking felt through the wheel, although this fades above 100 (discovered on a test track, of course) not sure if this could be a balancing issue.

The front tyres are 225/50/16 Avon ZZ3.

The penalties I'm paying for these wheels seem to be just too great, so theres a strong possibility they'll be coming off again

No complaints with the toyos, though, they seem very capable, although I've not pushed them too hard as they're new.

[HerefordMark]

My XJRS on the same tyres also does this - makes for some hairy moments. I have been told that careful setting of toe-in will alleviate it, but wider tyres will always tramline more than narrow ones. I haven't tried it yet - damned thing is a long way from sniffing an MOT...