Split rim alloys - triumph of style over substance?
Discussion
I'm a long-time owner of XJS and XK8s (none bought new and none with any cool alloy wheel upgrades) and I have recently been looking at 4-5yr old XK8 convertibles. One such looked nice in all respects except that it needed a lot of steering correction on an uneven road to prevent it following the bump contours into a ditch. The owner told me that it was because of the 20in Detroit split rim wheels which have a tendency to follow the contours -- unlike my bog standard XK8 alloys which hold a much straighter line on the same kind of surface.
Question is: was he spinning me a line or are these pretty, low profile tyres renowned for this tendency? I did speak to an honest ex-Jaguar salesman who went as far as telling me that these expensive wheel options are a triumph of style over substance and that I would not get any better handling out of them than I get from my boring wheels. But he didn't go as far as saying that they require a lot more handling on poor roads...
I'd be grateful for your advice on this. I guess if I don't like the way the wheels handle, I can always switch them but then it seems a bit crazy to pay a premium for them in the first place.
Question is: was he spinning me a line or are these pretty, low profile tyres renowned for this tendency? I did speak to an honest ex-Jaguar salesman who went as far as telling me that these expensive wheel options are a triumph of style over substance and that I would not get any better handling out of them than I get from my boring wheels. But he didn't go as far as saying that they require a lot more handling on poor roads...
I'd be grateful for your advice on this. I guess if I don't like the way the wheels handle, I can always switch them but then it seems a bit crazy to pay a premium for them in the first place.
I don't know what size tyre the Detroit alloys take, but it's generally the case - all other things being equal - that wider, low profile tyres do tend to follow tramlines and wriggle about over bumps a lot more than a narrower tread width higher profile tyre.
They also tend to give a much more nervous twitchy ride, and IMO make a considerable contribution to driver fatigue - but I think so many people have got used to the charecteristics of low profile tyres nobody comments about the poor ride quality anymore.
I recently drove an old diesel Vauxhall Omega estate with slim, high profile tyres, softish suspension and small - relative to the tyre size - wheels. OK, so it didn't handle very well but bit gave a lovely smooth and comfortable ride - and was more relaxing to drive on the crappy roads we have in the UK than my XJ is.
There's quite a difference in ride quality between the 17" rims and 235/50 profile tyres and the 16" rims and 225/60 profile fitted as standard to the X308. I've swapped the two sizes over (same make) on the same car and was quite surprised just how much the ride improved with a relatively small profile change.
They also tend to give a much more nervous twitchy ride, and IMO make a considerable contribution to driver fatigue - but I think so many people have got used to the charecteristics of low profile tyres nobody comments about the poor ride quality anymore.
I recently drove an old diesel Vauxhall Omega estate with slim, high profile tyres, softish suspension and small - relative to the tyre size - wheels. OK, so it didn't handle very well but bit gave a lovely smooth and comfortable ride - and was more relaxing to drive on the crappy roads we have in the UK than my XJ is.
There's quite a difference in ride quality between the 17" rims and 235/50 profile tyres and the 16" rims and 225/60 profile fitted as standard to the X308. I've swapped the two sizes over (same make) on the same car and was quite surprised just how much the ride improved with a relatively small profile change.
For the last 5 years I've had XKR's with 20inch rims. The only time I have ever noticed any 'tram lining' is when driving down the inside lane of the M25 and getting caught in the truck grooves. Also on a minor roads, if there is adverse camber to the road surface the car may want to pull, but this is very minor. I personally think the Jag rims are fabulous for ride and driving control. So in answer to your question, I'd say somethings up.
G
G
Edited by Triple7 on Monday 14th April 20:21
T7 has a very good point though, it could be a case of worn lower wishbone bushes affecting camber, a selection of tired, pick and mix tyres, incorrect tyre pressures, or general geometry miss-alingment causing the problem.
Larger wheels and lower profile tyres transmit more energy to the suspension components which accelerates wear. As Jaguar ride quality is usually so good it's often the case suspension wear is a subtle process that's hard to diagnose the point at which somthing is clearly wrong. I'd suggest if you're serious about buying the car that you try driving other similar ones with OE wheels and tyres.
Assuming there are no specific problems with the car you drove this will give you a better comparison and feel for the effect of the larger wheels.
If the worst comes to the worst, you could always stick the Detroits on ebay and buy some standard rims, I expect they'd be snapped up as they are considered highly desirable and you shouldn't have any problems finding replacements as you'll be going in the opposite direction size wise most people do when changing wheels.
As soon as a good set of 16" wheels come up at the right price, that's what I'm planning to do with my 17" Celtics.
Replacement tyres are much cheaper too...
Larger wheels and lower profile tyres transmit more energy to the suspension components which accelerates wear. As Jaguar ride quality is usually so good it's often the case suspension wear is a subtle process that's hard to diagnose the point at which somthing is clearly wrong. I'd suggest if you're serious about buying the car that you try driving other similar ones with OE wheels and tyres.
Assuming there are no specific problems with the car you drove this will give you a better comparison and feel for the effect of the larger wheels.
If the worst comes to the worst, you could always stick the Detroits on ebay and buy some standard rims, I expect they'd be snapped up as they are considered highly desirable and you shouldn't have any problems finding replacements as you'll be going in the opposite direction size wise most people do when changing wheels.
As soon as a good set of 16" wheels come up at the right price, that's what I'm planning to do with my 17" Celtics.
Replacement tyres are much cheaper too...
Thanks all for the helpful advice. Car vendor says he will pay for a full, multipoint Jaguar PDI on the car but I'm not certain what that covers. Will it include checks on the bushes, tyres and wheel alignment?
As for selling the wheels - when I compared Parkers guide prices for the car with and without the Detroit option, it seems they add a whopping £1500 to the value, even on a 5yr old car. Does that sound right? Or how much should I expect to get for them in good condition? I could improve them by replacing the rims which have a few scuffs on each wheel but those rims seem to cost £200 each... (It seems to me that the rims are always prone to damage since they are proud of the rubber and are therefore the first point of contact -- unlike my high profile tyres where the rubber takes the first hit on a kerb.)
Wondering too whether the proceeds on a 5yr old set of 20in Detroits might cover the cost of a new set of high profile 17in alloys...?
As for selling the wheels - when I compared Parkers guide prices for the car with and without the Detroit option, it seems they add a whopping £1500 to the value, even on a 5yr old car. Does that sound right? Or how much should I expect to get for them in good condition? I could improve them by replacing the rims which have a few scuffs on each wheel but those rims seem to cost £200 each... (It seems to me that the rims are always prone to damage since they are proud of the rubber and are therefore the first point of contact -- unlike my high profile tyres where the rubber takes the first hit on a kerb.)
Wondering too whether the proceeds on a 5yr old set of 20in Detroits might cover the cost of a new set of high profile 17in alloys...?
I am assuming that with your 20inch alloys you also have the 'Brembo' brakes. If you do, you won't be able to fit the smaller alloys over the bark callipers. You would then need to change the brakes, which require a change of hub etc. i.e. big money, so whats the point? Keep the 20inch wheels, they make the car look fabulous, the drive is different to what you normally have, but you'll soon get used to it.
The PDI will only check those items you are concerned with if you ask specifically.
G
The PDI will only check those items you are concerned with if you ask specifically.
G
:-) No, two different cars. I'm basically a doddery old codger who values comfort over performance - as long as the comfort comes with style. So I don't need a supercharger and would probably only rarely appreciate the full benefit. But I want as close as possible to silence when idling and cruising. The R vendor told me that that the supercharger was "always on", unlike turbo which kicks in - and it made me wonder if it therefore added to the ambient noise at the times when I like quiet.
pr100 said:
:-) No, two different cars. I'm basically a doddery old codger who values comfort over performance - as long as the comfort comes with style. So I don't need a supercharger and would probably only rarely appreciate the full benefit. But I want as close as possible to silence when idling and cruising. The R vendor told me that that the supercharger was "always on", unlike turbo which kicks in - and it made me wonder if it therefore added to the ambient noise at the times when I like quiet.
My XKR is really quiet, and I only notice the supercharger when accelerating. Other than that its fine for idleing along at 1500 - 2000 rpm.pr100 said:
:-) No, two different cars. I'm basically a doddery old codger who values comfort over performance
I don't believe you! If that was the case you would be looking at a new shape XJ or a Honda! 
The supercharger makes no noise unless under hard acceleration, believe you me once you have felt the rush there is no going back!
So go get a drive in a different XKR convertible and let the proof be in the pudding.
G
Triple said:
I don't believe you! If that was the case you would be looking at a new shape XJ or a Honda!
Funny you should say that - I haven't completely ruled out an XJ 
Triple said:
So go get a drive in a different XKR convertible and let the proof be in the pudding.
One is coming to see me in an hour's time: 2002 XKR with only 27k on the clock but with only an occasional Jaguar service stamp (last one was early 2006) as the owner's friend carried out most servicing including one last month... He did say he would get a Jaguar PDI and Jaguar MOT put on it though so I'm tempted at around £20,000.It gets worse... The car drives well but it was originally imported by a leasing company and the lady who leased it until 2005 had it serviced at her family-owned garage rather than by Jaguar so apart from the original PDI it has never had a Jaguar service stamp. The car was then auctioned (normal practice with leasing companies I think) to the present owner who paid £32k for it in 2005 when the mileage was about 15000. He too had it serviced privately (family firm again) but it has got a couple of Jaguar inspection receipts (no advisories) from 2005 and 2006 when it went in for repair.
I couldn't find much wrong with it (but I'm not a good judge) except that there was a film of oil over and around the surpercharger and the tyres were a brand I've never heard of (and immediately forgot). He's putting it in for a Jaguar MOT and PDI tomorrow so that should tell me more.
Still tempted at £19-20k though, even if it obviously has been maintained on a shoestring... Must I be crazy?
Anyway, coming back to the topic, this car had wide tyres (not especially low profile though - see pic below) and it didn't track as much as the XK8 with split rims I drove the other day; also the engine note was much quieter than the noisy XKR I raised in my other tread.
I couldn't find much wrong with it (but I'm not a good judge) except that there was a film of oil over and around the surpercharger and the tyres were a brand I've never heard of (and immediately forgot). He's putting it in for a Jaguar MOT and PDI tomorrow so that should tell me more.
Still tempted at £19-20k though, even if it obviously has been maintained on a shoestring... Must I be crazy?
Anyway, coming back to the topic, this car had wide tyres (not especially low profile though - see pic below) and it didn't track as much as the XK8 with split rims I drove the other day; also the engine note was much quieter than the noisy XKR I raised in my other tread.
If you're serious - and not sure about this particurlar XK - I'd spend some cash on an independent inspection, and get soembody who knows the XK range to have a long hard look at it.
With the economic downturn - real or imaginary - there will be loads of expensive to run cars coming on the market. You can afford to be extremely choosy and drive a very hard bargain.
With the economic downturn - real or imaginary - there will be loads of expensive to run cars coming on the market. You can afford to be extremely choosy and drive a very hard bargain.
My XKR does this and has Detroit 20" rims. A couple of things spring to mind. Tyre pressures need to be absolutley spot on. Bottom shock absorber bushes wear very quickly. Tracking should be done. Finally you could change the tyres to Dunlop SP Sport Maxx as used on the new XK as some XKEC members reckon they have better handling characteristics. I am having the bushes replaced and tracking checked on mine in a couple of weeks time.
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