GS Wheels

pottsy

Member
1000+ Posts
OK, today was a tyre day in the Shed.

To set the scene, while I was sorting GiSelle out originally I put a set of new Nankang tyres on her. Because of the rather sad condition of the lower arm bushes after a very short while, the fronts wore considerably on the outer edge. Once I sorted (or so I thought) the lower bushes the first time, I somehow managed to stuff up the toe setting quite dramatically, resulting in more wear on the outer edges of the second pair. End result, all four boots are looking a bit second hand.

I'm now confident that I've got the lower arm bushes right, and the toe setting is to spec.

So I've bought a set of four new ones, the same type again since they're available an relatively cheap. ($80 each plus delivery from Tyroola in Sydney)

Since a couple of the ones on the car are still quite usable, and my spare wheels had old Michelins of indeterminate age on them, (They pre-dated the DOT dating mark standard!) I decided to strip the spares and fit the new ones to them.

Yes, I know I could just trot down to the tyre store, hand over a wad of readies and drive away refreshed, but part of being a Tinkering Loony is craving the satisfaction of doing things oneself.

First hurdle was to break the beads on the old Michies. The bead breaker integral in the generic tyre changer bolted to the floor just wasn't co-operating so I did a bit of lateral thinking. Who would have thought that a four post hoist with a D-Special on it would also be a really effective bead breaker? I positioned the tyre so that when I lowered the hoist, the bar would press down on the tyre and such it proved to be!

Onto the changer, a brushful of detergent around the bead and off they came. Now to the nub of my gist, so to speak.

One of the spares was fitted tubeless, while the other two were fitted with tubes. I know the front ones on the car at present are tubed, but I'm reasonably certain the rear ones are not. (Just went out to check and, unbelievably, both valves are at the top of the wheel under the wheel arch so I can't confirm at present).

Now I'm aware that tubeless tyres are only supposed to be fitted to rims with the "safety ridge" rolled into them to prevent the bead pushing into the centre well in the event of major pressure loss. This was why the front ones were fitted with tubes by the local tyre bloke because he reckoned they didn't comply.

Now that I've had a good sticky beak at these rims while cleaning them preparatory to painting, it seems to me that the outer "bead settling area" has a slope which to me would seem to indicate at least a partial attempt at providing the safety ridge concept. By this I mean that the surface between the edge of the centre well and the outer rim is actually sloping towards the outer rim. The photo shows it best I think.

So I seek the Collective Wisdom of the Brains Trust and crave guidance therefrom.

Has anyone else any input to offer? I would be reasonably confident that fitting the tubeless tyres tubelessly would not be an issue, but if that constitutes an infringement of an obscure ADR requirement I guess a tube can be inserted. I just would prefer to not have the hassle of tubes.

Any and all comment and guidance is welcomed.

Cheers, Pottsy.
 

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OK; here's the analysis.

First, having the safety ridges (one or two) is decidedly "a good thing". When a tyre is flat, or at very low pressure, the bead will tend to "walk" across the rim & fall into the centre trough. Thus one gets a rim-on-road scenario - not good, especially if one is in a corner. The safety ridges keep the tyre's beads from migrating.

So, what if one has not got them?


First, note that the only role for such ridges is when a tyre's flat or near so. When pressures are normal they do no work as air pressure keeps the bead of the tyre in place. This is so whether one has that air enclosed in a tube or sealed within the inner envelope of a tubeless tyre.

When pressures are low enough for a bead to migrate then you'd realise that something was wrong. Say, though, that you're insensitive & don't notice; is there an advantage in such a person having a tube?

Not really. At very low pressures, there is a considerable chance of a tube rupturing (from pinching or overheating). If this happens, then sudden air loss occurs. A tubeless tyre won't do this. Mind you, without normal air pressure maintaining a seal, one can get brief episodes of near flat tubeless tyres desealing (from road or lateral load inputs) & consequent air loss as the bead seal deforms before forming again. So far, a draw perhaps in the near-flat scenario. This scenario is the only technical reason for the suggestion that rims without the ridges should have tubes fitted & it's not quite thoroughly thought through &, in any event,swamped by other considerations. Note that if the bead does migrate into the well, then each tyre type suffers rapid loss of remaining air (any tube becomes swiftly ruptured).


Say one does not have a rim with safety ridges & has the tyre pierced by something like a screw. Either it stays struck in the tread or not.

Say it does.

In the case of a tubeless tyre, one might not even notice & the likely result is a slow leak. Not dangerous & easily remedied in due course.

In the case of a tubed tyre, & assuming that full penetration has occurred, the tube is ruptured & a comparatively rapid loss of pressure occurs via the valve stem hole. Certainly more dramatic & definitely potentially dangerous depending on what one was doing at the time.


Say that the screw (or whatever) pierces but then works out.

For a tubeless tyre, it will still likely be a slow leak but even if faster, it is not going to be as fast as the rapid loss from a ruptured tube unless a 1 cm hole is punched in the tyre.

So, summary to date: safety ridges only matter the tyre is near flat & in such a scenario the tube is of no help. Moreover, having a tube makes a tyre more vulnerable to road hazards.

But: say that, despite this, one wishes to fit a tubed tyre to such a non-ridged wheel. It might be that the only tyre available or the tyre that one really, really wants (it was original fitment & just looks so right!) is tube-type. This is technically sub-optimal & a tubeless type would be better in many ways but so be it.

Say, though, that one wishes to fit a tubeless tyre to such a rim (for argument's sake, a tubeless 165/80-15 Hankook K715 to a non-ridged 404 rim). Originally tubed tyres were fitted, so should one fit a tube? No.

The inside of a tube-type tyre is smooth. The inside of a tubeless tyre is ridged. The interaction of a tube on that ridged surface has two effects: chafing of the tube & heat generation. Both are causes of potential tube failure. And, recall, tube failure results in rapid pressure loss. It might be that chafing will merely cause some tube porosity & a consequential slow leak & thus that one will get some warning of a developing problem but things might move faster. Depending on vehicle use, tyre pressures, tyre ridge prominence & tube thickness one might even "escape the bullet" & not develop a problem. Fine; but however fortunate that might be, there are other potential issues with tubes (see above) & if one is going to fit tubeless tyres, then nothing is gained & much is lost (see above) by putting tubes in them.

So, in summary, if there's a choice then fit tubeless &, although ridged wheels are best, tubeless on non- ridged wheels is better than tube-type.

Incidentally, I suggest that, instead of the CX 668 Nankang, you consider the AS-1 in 165/65. Neither is a wonderful tyre (nor is XZX) but the AS-1 is the least worst tyre available to suit. You'll be undergeared a little (around 4%) but I suggest that that's a small price to pay for a better tyre.

I also suggest that you be wary of stock age if buying from Tyroola.


cheers! Peter
 

pottsy

Member
1000+ Posts
Wow that's some analysis! My thanks for a balanced argument.

Your conclusion sort of matches my own feelings, that it's better to run tubeless rather than risk a tube wearing on the inside of the tyre. I recall that this was always traditionally mentioned when considering the relevant merits of tyre fitting, and not recommended for fitment in tubeless tyres except in special cases. I imagine that the lack of the safety ridges is/was considered to be a special case, but I think you've made an excellent case.

On the other hand, the GS has zero offset geometry at the front so the chances of feeling a soft tyre may actually be smaller than would otherwise be the case. I guess a bit of belt and braces might be to fit a set of pressure monitors, which is an affordable option these days. I also reckon I'm experienced enough to be able to suss out a soft tyre pretty quick.

As to the choice of tyre, I've already bought the CX 668s, partly because they're what I have on there at present (so swapping tyres around is easier) but also because I really can't say they're unacceptable in few thousand km I've covered so far. Handling and grip is fine for my driving style so far. I've also used the same tyres on the 2CV and they are fine on that as well. I suspect my expectations are lower than many. :)

So I think I will probably fit them tubeless anyway, but not until I've cleaned and painted the rims.

Cheers, and thanks again, Pottsy.
 

Buttercup

D Stracted
1000+ Posts
I've been running tubeless on both 2cv and GS wheels for years, despite some hesitancy from the tyre shop they didn't refuse to fit them.
Never had a problem.
I don't often agree with the previous respondent, but here I think I do.
In every way you are better off without tubes.
I have Hankook 165/80-15 on the front of my 2CV/GS/DS composite car, and Nankang 145-15 on the rear, all tubeless on GS rims.
They are black and round and slightly squooshy. The Hankooks are probably better tyres.
 
As I've observed elsewhere, the case for good tyres is not just a matter of driving style. The cost difference is not huge & a way of thinking of it is as a form of insurance in the case of an unlikely event (swerving &/or braking, especially in the wet) when one's tyres being on one's side, as opposed to exacerbating the event, would be nice. Of course one's chances of that happening is much lessened by mindful driving but. . . (For that matter one's chances of having one's house burn down are much lessened by various prudent precautions but that's not a case for eschewing house insurance.)
Tyres vary greatly in their responses to urgent inputs. You might want to consider the AS-1 (or Kumho's KH27) in 165/65 next tyre change. Each is a decided step up from the CX668.

The most usual "special case" for putting tubes in tubeless tyres is if the wheels are wire wheels.
 

pottsy

Member
1000+ Posts
Thanks again chaps.

You've helped crystallise my thinking and tubelessly will be the "methode du jour".

I forgot to mention, Peter, that while I have heard yarns in the past about old stock tyres in slow moving sizes, these ones from Tyroola are all dated 2021 by the DOT code. (1321 which I believe is week 13 this year?) Incidentally, apparently the current DOT coding method came in around 2000, which re-inforces my feeling that the Michies that were gripping tightly to these rims were well over 20 years old.

The freshly cleaned and wire brushed rims are sitting in the sun with a coat of Penetrol drying on the inner surface. Not that the three rims in question are rusty, but there are a couple of spots that were worth tackling while the inside of the rim was accessible.

Haven't yet decided whether to paint the outer surfaces. I'm tempted to leave them in the original paint since they're not crusty at all and cleaned up quite well with the pressure washer. That, and the fact that very little of the rim is visible past the big Pallas hubcaps. (Don't want GiSelle to start looking like a show pony! :) )

Cheers, Pottsy.
 

davidetas

New member
Hi to all,

I still confused about tube yes or tube not. I will go soon to order a new set for the GS, and because my choice is Michelin I contact them for a clarification one for ever, I think they should have a proper answer. I don't like me either the idea of tube, also because the tyres Michelin but even the other brands Nankang are tubeless rated. The only problem, seem to be the steel rims, the alloy rims of the GSA they have a safety ridge and suit the tyres perfectly, but for me are impossible to find, I'm searching a set for a while, so I have to stay with normal steel. Also reeding the post seem that people mix the size. Can cause any problem, using different size from the original 145 R 15 write in any book?And maybe end up in some clearance issue front or back? If Michelin answer back, I will post the copy of the email, in the hope is interesting to the all GS owner.
Cheers David.
 

pottsy

Member
1000+ Posts
Well after an afternoon of tyre wrangling, I've got two brand spankers tyres fitted to cleaned and de-rusted rims.

Putting the tyres on the rims was pretty easy. With some nice slippery detergent they slid together neatly. (OoEr Matron!)

Seating the beads was another story. It took a while to achieve. I tried the old ratchet strap trick but that was a bust. I certainly will never stoop so low, or value risk so high, as to use the ether and a match method!

In the end I went the "stand them up and weasel the tyre a bit while running air in to the max" method, which worked.

Finally, with enough slippery stuff, and the compressor ramped up to 11, I was able to bring them round to my way of thinking. :)

And curiously, on my home made bubble balancer, they appear to be pretty much balanced. Time will tell.

Beer O'Clock I reckon! Cheers, Pottsy.
 
Glad all has went well Pottsy.

On tubeless with steel rims: the only issues are not to do with safety ridges but to do with slow leaks. Two sources:
First, if the wheel centre & rim are riveted together, then air might leak around the rivets. The solution is to seal that area with goop.
Second, if the wheel is out of round or damaged, then the bead area might leak. The solution is to ensure it is "true" (wheelwright-job) &, again, to "goop" as necessary.
 
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