Alloy Wheels

[beachcomber]

Hi Ciaran,

If you like Wirdy's wheels then I suggest you buy yourself a set of Volvo Centaur's. As far as I can see , they're IDENTICAL. My pal has borrowed my 965 Estate, but when it comes back I'll have a look at the manufacturer of the wheels - might even be Speedline! See my previous post re: the ones just sold on e-bay.

These are a direct fittment for the XM but do check the offset.


Both my XM saloon and XM Estate were perfect on 55 series tyres [ 225 section ] and without any problems. Roadholding, especially in the wet was improved and no detriment in the handling dept. In fact they seemed to really suit the estate.
Beachcomber

[Ciaran]

I must admit to being quite ignorant of the whole wheels thing, and what offset is needed, and how this affects the car, etc. Anyone care to elaborate?

[beachcomber]

Hi Ciaran,

in simple terms "offset" is the position of the wheel centre relative to the hub face and outer face of the wheel.

It's described as "positive " or "negative". Essentially, it boils down to how far out the wheels stick!

RWD cars typically have a lower offset value. Conversly the reason for the "inset" or higher figure on FWD cars is that the position of the wheel helps with torque steer. Typically if you fitted a really wide RWD wheel [ as the Ferrari - which will fit an XM ] to a FWD car then the additional mass of the wheel further out from the hub creates a multiplication of the torque. This manifests itself by way of the steering wheel trying to rip itself out of your hands when you corner and boot the throttle at the same time.

Either way no probs with an XM in terms of overabundant power or extremely wide wheels! Neither apply to an XM!

beachcomber

[Ciaran]

Thanks very much for that Beachcomber, makes sense now

Cheers for mentioning the Volvo wheels also, I'm going to look out for a set, as I imagine they may be a tad easier to get hold of than the Alfa ones!

Cheers.

Ciarán.

[beachcomber]

Hi Ciaran,

good luck with the search. Wirdy had a fantastic deal with his Alfa wheels, but bear in mind the extras that he had to purchase to get them to fit - still worked out a bargain though.

I can imagine that a set of Volvo Centaurs should be available for the same sort of price as the Alfa wheels alone, especially if you're prepared to wait. I looked at a COMPLETE car 3 weeks ago for a friend - 740 Estate - and it had a set of Centaurs with good tyres - the WHOLE car was only £200 !!! You could have bought it, exchanged wheels and sold the Volvo for what you bought it for AND had a set of FREE wheels!

There is 1 Renault Espace wheel that I want to try, its a broad flat 5 spoke wheel, and I think might be quite attractive on an XM. I already have a set on my 3 ltr. Espace, but I recently saw a set for £125 ono with excellent tyres.

Not certain if I mentioned in the previous data - the Renault uses a 15 mm stud as opposed to the 13mm of the XM / Volvo - so if people look at Renault wheels they need to bear this in mind. I have a feeling that the Ford also uses a 15mm fixing. No big deal, but just be certain to use the correct fixing for the WHEEL, not the car, this could mean buying aftermarket fixings.

Fortunately these days MOST manufacturers use the same taper with alloy wheel fixings - those of you familiar with CX's will know they have a wierd washer arrangement. HOWEVER, if you don't want to run the risk of a wheel overtaking you one day - be absolutely certain that the taper for the fixing you use matches the wheel.

In the Good Old Days I was involved with American Muscle cars [ Mustangs, Corvettes, Dodge Hemis, etc.], and many of the US manufacturers had different fixing tapers. To add to the confusion, UK aftermarket wheel manufacturers [ predominantly WolfRace ] used yet another taper. This DID result an many a wheel flying off a car at an inopportune moment!

The moral here is double check everything - then double check it again
beachcomber

[Ciaran]

What a good idea, I often see whole cars even with test and tax going for silly money. Set of wheels from a scrappy and the whole thing can be sold on again....

I'll have to be careful with the spec of the bolts, as you mentioned. Are there any resources where you can find out which types of wheels are a particular size, or should it be blatently evident when you go to fit them?

I've swapped wheels before, but they've always been like marques, so never really encountered problems...

[beachcomber]

Hi Ciaran,

there should be NO issue with a Volvo to XM swap.
Use the Citroen studs and double check the taper on the shoulder - it should be obvious if they are different.

Can't check it for you as my pal is still borrowing my 965 Volvo!

You'll probably want a set of locking wheel nuts anyway. Try a motor factor rather than Halfords or similar - they are related to Dick Turpin!

If you are not in any particular rush, I expect to get my 965 back within the next 2 weeks.

Beachccomber

[DerekW]

OH Gawd! I'm going to show my age here! Why is the whole world obsessed with alloy wheels?

I've got the original ten-spoke Monaco wheels on my car and they're (IMHO) ugly and difficult to clean. But why alloys in the first place, other than to keep up with the Joneses? When you're travelling at the speeds the XM was designed to go at, the wheels are a blur anyway.

It seems to me that there are two major considerations when considering wheel design, the weight of the wheel (unsprung weight has a major influence on ride comfort) and stiffness (for accurate steering). I'm aware that some light alloys have a higher strength-to weight ratio than steel but how about the stiffness to weight ratio? I've just lugged the alloy wheels off and onto my wife's ZX and believe me, they're a lot heavier than steel wheels. Perhaps the manufacturers had to use more material to achieve the required stiffness?

And then we come to stress raisers. Steel is a very forgiving material with a high Griffiths crack tolerance, whereas light alloys are notoriously prone to fatigue (ask anybody who's had any dealings with the wonder material titanium on Lynx rotor heads). What material is used in these alloy wheels? I don't think it's dural so it's probably a mag alloy - and that material is prone to corrosion, just the thing to use on salt laden winter roads. I believe the first car to use mag alloy wheels was the "flat iron" Lotus 18 formula 1 car (1960/61) but they changed the wheels after every race.

My first XM had steel wheels with those one-piece plastic covers with little hinged flaps to cover the valve. They were easy to clean and always looked smart and I noticed no deterioration in ride or handling compared to my current car.

Sorry for the somewhat disjointed ramble, but back to my opening paragraph. Why is the whole world obsessed with alloy wheels?

That, hopefully, has put the cat among the pidgeons!

Derek

[bigjohnh]

Derek,

I agree wholeheartedly with your sentiments, I am also a fan of steel wheels and have wondered on many occasions why manufacturers don't just make attractive steel wheels with maybe a small hubcap to protect the nuts. I fear that it is the drive to sell us something we don't need. Even plastic wheel covers get lost or cracked whereas a nicely made steel wheel is resistant to curbing and more air proof than an alloy wheel. Up until the late 60's/early seventies most cars had good looking steel rims with occasionally plated steel or stainless hubcaps. Do you remember such classics as Rostyle or Wolfrace wheels. Love them or hate them you could damage them enough to bend the rim and they remained airtight and usable.

John

[beachcomber]

Derek W,

well my old codger mate - I don't think I'm far behind you at 63 - but I'm not entirely certain what it is you are unhappy about re: the subject of Alloy wheels?

As to durability, I have a set of Wolfrace wheels that have been fitted to many diverse cars since 1974 - and showing absolutely NO signs of fatigue at all.

And I wouldn't say they've had a particularly easy life, being used on amongst others a 400 bhp Drag Racing Mustang. Salt corrosion? Also not a major problem, in 32 years I've had them re-polished once.

As to WHY - that's a different matter - the desire to be different I guess - probably one of the reasons you chose an XM rather than a Granada or Senator.

Heavier than steel? Undoubtedly - handling and etc. "at XM speeds" - hardly a problem, we're not talking rocket ships here are we!

"Stiffness for accurate steering" give me a break - have you seen how much rubber and compliance is in the average modern car's suspension and steering?

Ah yes, the one piece plastic covers with the little flap. Is that the one where you either broke your nails or got covered in brake dust every time you wanted to check pressures / inflate tyres?

Steel is a very forgiving material - perhaps we should explain that to my pal who has just had a wheel failure [ mounting holes ripped ] on his Brian James trailer - Griffiths must have missed that one.

However, I have a solution for you - I am quite prepared to sacrifice my standard steel rims and beautiful plastic covers in a straight swap for your alloy wheels - can't be fairer than that?

Now then to your fan BigJohn

Err a slight terminal inexactitude pardner - WolfRace wheels are cast alloy - not steel and would certainly bend up to a point but would then crack - usually breaking a piece off. And Rostyles - a two piece wheel that had a rim rivetted to the centre - even with Cortina power these would often rip the centres out when driven "briskly". In fact they were BANNED from use in racing in the 60's for that very reason.

Back in the '60's, Chevrolet used some very attractive "Kelsey Hayes" steel wheels as did Ford on some of their Mustangs. Similar in style to the Rostyles, but were WELDED rather than rivetted together. A solution to the Pretty steel wheel. However they were also considerably heavier than the original wheels and also the WofRace wheels that I replaced them with on one of my Mustangs.

Finally as to forcing people to buy something they don't need - just say no.

And finally to pricing - if you're feeling really miserable and dejected one day and you want a real laugh - call your local friendly Citroen dealer and ask the price of a new standard steel wheel and plastic cover. I gurantee you'll drop the phone with all the laughter.

No guys, at the end of the day it's personal choice and the desire for some of us to be a little different from the herd. Nothing wrong with either approach.
beachcomber

[DerekW]

Thank you, bigjohnh for your support.

Beachcomber, I thought I'd made it obvious what I was unhappy about; the idea of using what appeared to be a styling gimmick which had so many obvious disadvantages. To whit, weight, difficulty to clean, tendency to corrosion and proneness to visual deterioration.

I suppose I was hoping for some esoteric physical reason why they were so popular, but you summed it up - the desire to be different. A superficial addition to be added to go-faster stripes, coke can exhausts, fluffy dice et al.

I will try to answer your comments in turn:

Rocket ships? 140mph+ isn't bad, although I haven't exceeded 120 in mine. There again, if we're talking about handling, 30mph around some corners and road surfaces requires good handling.

"Stiffness for accurate steering". Whilst agreeing that there is compliance built into the suspension system, I can find none between steering wheel, column, rack, track rods, track rod ends and road wheel. Can you? I think (I may well be wrong) that the lightest wheels were those with wire spokes, popular on sports and racing cars up to the '50s. I also understand that there were two reasons for their demise, lack of lateral stiffness and the advent of the tubeless tyre - although it would have been feasible to vulcanise a rubber strip inside the well to seal the air in.

A.A.Griffiths was of course concerned with crack propagation and it was in that context that I referred to steel as a forgiving material. It would appear from your description (tearing) that your friend's wheel failure was caused by exceeding the UTS, not by cracking.

Although I was tempted by your offer to swap wheels, there are two reasons why I cannot accept. Firstly because, when (if) I get around to disposing of my car it would be off spec, and therefore worth less. Secondly, because I am unsure whether the the steel wheels would accept the larger tyres fitted to my car.

Derek

[beachcomber]

LARGER TYRES DerekW???

No mention of THAT in your diatribe on alloy wheels, and you state wider tyres as being a reason to keep your "styling gimmick" alloy wheels? Confused.com.

IF the alloy wheels are THAT much of a disadvantage in your view [ cleaning, corrosion, stress, flexing ] why not put a set of steel wheels on to make you feel more comfortable - and keep your alloys in a nice dry non corrosive atmosphere until you sell the car? 205's will go on std. steel wheels with no problems and according to your thesis - your handling will be more precise. Not only that, people will not think of you as a superficial person with your gimmicky alloy wheels.

That, of course is a GIVEN for a reason to fit aftermarket [ or OEM come to that ]wheels, as MOST OEM manufacturers only give you a choice of wider ALLOY wheels as optional eqipment to the standard steel versions.

Next time you start up your XM and turn the steering wheel at rest, see just how far the wheel moves on those squiggy tyres [ wider? ] before any change of direction is accomplished. I guarantee the tyres will deform before the lack of stiffness of the alloy wheel forces it to do the same! As to no compliance in the steering system - err that works in conjunction with the suspension system which actually holds the wheels in place [ 'ish ]. Try moving ANY of the suspension control arms that support the hub [ ALL rubber mounted incidentally ] and see how far the wheel moves around. You are applying race car logic to a squiggy saloon car - apples and oranges.

As part of my "day job" [ now semi-retired ] I am an auto design engineering consultant - my last job being to to design a rolling chassis for a Porsche 550 replica, and prior to that, involved in the redesign of the suspension and steering on a well known German Cobra replica. I am currently working on a Mercedes Gullwing 300 SL Coupe. [ www.gullwing.ch ] and a 904 Porsche - both replicas.

One of the biggest problems we encountered with the Cobra was to arrive at a satisfactory means of attaching the STEERING RACK to the chassis. The design of the car was erring towards Competition rather than roadgoing. We found that with all the Poly bushes, Rose joints and other fairly solid bearing mediums, the one that gave us the biggest headache was the steering rack mounting. The original OEM [ in this case Ford ] solution was to insert rubber bushes between the mounting and the rack. This mounting actually enclosed the rack. The amount of deflection between the solid steering column [ with obligatory crush zone ] and the rack was visually apparant. The whole rack would rotate about it's horizontal axis when the wheel was turned by as much as 1/4". This in turn affected the position of the inner steering rod end relevant to the hub and thus resulting in a change of the [ designed out] bump steer. We then went to poly mounts which improved the situation [ 1/8"], and in our case had to be a compromise for roadgoing use. For racing this is replaced with alloy blocks.
It's common practice to replace as many rubber bushes on an OEM car with poly bushes in an attempt to eliminate deflection in the steering / suspension when attempting to improve the handling / roadholding.

See also the Bardahl race Cobras and the Shelby approved Cobra - both of which I had a hand in [ the Realm Engineering site ].

How is the steering rack mounted on an XM? OOOps - you may be wrong, or I could be wrong - but I'm guessing rubber.

Steel spoke wheels - actually surprisingly heavy. My pal [ Realm Engineering www.realmengineering.com ] manufactures Jaguar "C" Type replicas [ and "D" Type / XKSS ] and has been involved with spoked wheels for the last 25 years. He now actually distributes a range of spoked wheels for the cars - but his biggest - by far - seller, is the ALLOY "D" Type replica wheel. The only wheel I've come across which is close to a lightweight alloy wheel [ as opposed to a "cosmetic" wheel ] were the Borrani Alloy rimmed spoked versions that were fitted to a Pantera that I owned 24 years ago.

I have been a design consultant involved with the various products displayed on his website [ sorry I STILL can't post pix ] for nearly 30 years. He has been selling these wheels for a number of years now to owners of Replica and Real cars alike as a practical and SAFE alternative to spoked wheels. The biggest problem with spoked wheels is the natural tendancy for the spokes to come loose. Speak to any owner of spoked wheels and they'll tell you that they have to have them checked at least once a year. Oh yes, he's the same guy with the Brian James trailer. I had a close look at the wheel in question yesterday. One mounting hole showed signs of a stress crack, whilst the other 3 holes were actually ripped. It was only the 3rd. wheel nut that stopped the wheel hurtling off into the undergrowth - fortunately there were 3 other wheels! On checking, one of the other wheels has the first signs of "spider" stress cracking on the mounting stud holes.

XM's - 140mph PLUS ? - Yes if dropped out of the hold of a Jumbo Jet. I presume you are referring to the V6 version of our favourite car, as my 2ltr turbo VSX tops out at 120 and my old TD 2.1 - 115mph .

When the V6 became available I had a saloon on extended test over a long weekend, fully run in and just serviced. 130 mph [ assuming an accurate speedo ] - eventually, YES - 140 PLUS mph, NO CHANCE [ I'm guessing yours is the faster manual version? ]. Come on all you V6 owners - HONEST max. top speeds? Anyway, get over 120 mph and the bloody side lamps fly off!

I've subsequently driven several V6's in both saloon and estate - 130mph was the max I ever achieved [ speedo reading ] in any of those cars. Excellent acceleration, good cruising speeds and towing ability are my main reasons for looking at the V6 for my own use.

I have had many cars fitted with versions of the PVR V6 - Renault 25 [ turbo ], 30, Espace, Volvo , Oh yes and an Alpine GTA Turbo. The Alpine was the only one to see the dark side of 140mph [ 160mph - chipped - and actually timed at 161 mph ] and that was HALF the weight of an XM. Admitted the Espace does have the aerodynamics of a brick - but there seems little practical difference in the top speed of the TD or Petrol 2ltr on that model - acceleration is a different matter, as is cruising speed.

I am currently looking for a V6 or 2.5 TD to live in Germany, and only last week drove a 1997 V6 Estate, the owner said that he maintains a steady 110 -120 mph on the Autobahns [ and he had seen just shy of 130 on the speedo] - THAT is a more practical figure to look at as my 2 ltr is "comfortable" at around only 100mph.

By comparison, my old CX [ 2.4 Inj. Safari ] would quite happily maintain 120 mph on long trips across France and Germany.

So DerekW - I think we need to agree to disagree on the virtues of alloy wheels. However, I DO agree that the stock alloys on your car ARE ugly.
Beachcomber

Even more cats and even more pigeons.

[DerekW]

When I read your latest missive my first thought was to ask you to read my posts with more care so that you did not misunderstand them, and suggest that you stop putting words into my mouth.

But then I decided to drop the whole thing - its not important and no one's interested.

Incidentally, you're eleven years behind me.

Derek

[jorgy9]

Come on you guys, the topic raised is interesting indeed, and there has to be objective answers to it -which is not so relevant to how old we are!-

For my own limited experience -u both are "holy monsters" compared to me!-, I'd say that there are alloy wheels that have benefits compared to a steel, but there are also alloys that are indeed worse -cheepos usually-. When I fitted cheap alloys (TSW was the brand) on my -don't laugh!- Clio 1.4, I noticed the difference on the bumps/holes at the *first meters* of my drive out of the shop! Very smooth! So a very practical reason there for switching to alloys, that really added value to my everyday driving (not at 140mph!). Although, technically, alloys should deform a tad more than steel wheels when turning -ur average car today achieving about 0.6-0.8G's-, I didn't notice a difference in handling in terms of alloys deforming, and I doubt if anybody could, to be honest. On the other hand, they alloys do need a (preventive) "straightening-back" every couple of years or so -or after having fallen into a biiiig hole-.

The aesthetics are a personal matter. There are both beautiful and ugly,, alloys and steel wheels. It depends on the precise combination of alloy and the car. Perhaps alloy is a bit more flexible in design terms? Aesthetics are important to me -in anything that surrounds me- so I like my car to be beautiful. If others do it for "being different in your face", that's another breed of people, with other views of life etc. But then one could say the same for myself ("big deal, your car and your alloy wheels, when children die in Africa at every second"). So all is relative.

Finish quality and endurance, should again be taken case-by-case. Both steel and alloy rust if they are not well finished.

I don't think you two guys really disagree in anything really, but you do shed light on different spots of the topic. I'd fit to my car a good steel or a good alloy, equally as I wouldn't fit a bad steel or bad alloy. I still have the impression though that (good!) alloys can potentially be significantly lighter than a steel and that this is the primordial reason they have been introduced to the market?

regards
George

[jorgy9]

PS. beachcomber, ur last email should be nominated for the longest email on this list ever -am I right people?-