tyres for 4 x 15 wheels
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Thread: tyres for 4 x 15 wheels

  1. #1
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    Default tyres for 4 x 15 wheels

    A range of rear-engined Renaults from the first 4CV to the last R10 used 4x15 wheels (spider or 3-stud) or 4.5x15 (R8S, R10S, R8G & various Alpines). Many folk abandon them for wider 15" wheels or 14" (my preference for reasons explained in another thread) or 13". But many retain the standard wheels.

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    This causes a problem when it comes to tyres. Many choose to fit Michelin ZX in 135/80-15 or XZX in 145/80. Or fit some other brand in one or other of these sizes (like Nankang). Or move to 155/80 (say, the Vredestein Sprint Classic). One can, with 4.5 rims, even fit 165/65-15 (a terrible Maxxis or the semi-decent Kumho KH 27).

    Elsewhere, I have argued against any of these options for 4" rims on a R-ER on wet grip grounds (laterally & braking at the front) & suggested that, for standard 4" rims, the best option is to suffer mild undergearing (-4.6 % compared to 135/80) & fit 145/65-15 (early Smart fronts). Of the limited choices available, the best choice for wet grip is Continental's EcoContactEP (there are other choices, like the Nankang AS1).

    All of which is preamble to pointing out that, until the end of October, Continental is having another one of those periodic (& delightful) "buy three & get one free" deals that seem to be becoming popular among manufacturers.

    Thus, if any of you have 4x15 wheels with worn or old (>1O years) tyres (look at the sidewalls for the manufacturing date stamp - guidance on finding it on request), then I think that now is a good time for remediation. [Incidentally, as also gone through in another past thread, fitting tubeless tyres to your wheels (spider or 3-stud, riveted or welded, with safety ridges or not) is legal, technically feasible & desirable. The worst that you can have happen is a slow leak if you have a distortion in the bead area (get it trued) or an air passage around the rivets (seal that area). In no event, should you put tubes in tubeless tyres (it's dangerous).]

    cheers! Peter

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    COL
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    Hi Peter

    Have a read here Tube fitment | Avon Motorsport
    Regards Col

    1973 Renault R12 Station Wagon
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    4cvg, what effects does undergearing have on the car?

    Col, that was interesting to read but self contradicting.
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    Quote Originally Posted by minigordini View Post
    4cvg, what effects does undergearing have on the car?

    Col, that was interesting to read but self contradicting.
    It points out the pros and cons of fitting tubes.

    If you undergear a car by fitting a smaller rolling circumference the engine will rev a little higher for the same road speed, which will cause a little more cabin noise, slightly higher fuel consumption and a speedo error.
    Regards Col

    1973 Renault R12 Station Wagon
    1976 Renault R12 Station Wagon
    2002 Renault Laguna V6
    1973 Alpine A110

    http://alpine-a110.weebly.com/

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    I consider that to be a poor document. My comments are interpolated in bold.


    "Guidance on tubes in tubeless road tyres

    Tubeless tyres in good condition, both new and retreads, fitted to the appropriate wheels and operated correctly, do not need inner tubes however there are some circumstances when it is useful to use a tube. When tubes are fitted, it is important for the user to understand the potential drawbacks.

    When a tubeless tyre is punctured, the penetrating object is gripped by the inner liner (the built-in tube) and thus air loss through the penetration will be gradual. By contrast, when a tube type or a tubeless tyre fitted with a tube is punctured, once the tube is penetrated, air loss will normally be sudden. In this case, air will rapidly escape through the valve hole in the wheel and between the tyre beads and the wheel which, with a tube fitted, no longer provides a hermetic seal. Sudden pressure loss in a tyre can result in bead dislodgement and a loss of vehicle control.
    When a tube is fitted to any tyre, it is important that the inside of the tyre is carefully examined to ensure that there is no feature which could cause premature tube failure due to cuts or chafing. Such examples are:-
    Any tire manufacturer’s paper or plastic identification labels must be removed and label indentations buffed smooth.
    Damage to the inside of the tyre, possibly due to a previous penetration or repair can lead to chafing of the tube and subsequent failure.

    This is bizarre & incompetent of Avon. They raise the issue of chafing & fail to note that the inside of a tubeless tyre is standardly ridged in a way that is not the case for a tube-type tyre. This is a recipe for chafing & for undue heat generation, both causes of tube failure. Presumably they are not recommending a total "buff it smooth" operation but why not? The ridges are worse than label indentations.

    The increased thickness of the tyre / tube assembly can cause running temperatures to increase and could under prolonged conditions cause premature tyre failure.
    Not withstanding the potential hazards, there are circumstances when the use of tubes may be recommended. The following points should be noted:

    Inner tubes must be fitted to all tyres that are NOT marked as “Tubeless” and to all tyres marked as “Tube Type”.
    Always use a new tube in a tyre with matching size marking.
    NEVER install a non-radial tube in a radial tyres
    Inner tubes should also be used:
    Where tubeless tyres are fitted to non-safety wheels

    By 'safety wheels' is meant wheels with either one bead retention ridge or two in the edge area of the rim. These are a good thing but play no causal role unless a tyre is severely deflated (in which case they prevent the bead wiggling its way across & falling into the central well, causing rapid loss of remaining air). So, a good thing but causally neutral in the case of an inflated tyre. And one should notice deflation in a rear-engined Renault before that point ("dragging to one ride" steering or an unusually wayward tail).

    Adding a tube does nothing to increase safety in the inflated scenario. What's holding the bead in place is air pressure & adding some thin rubber is irrelevant to that in a tubeless tyre. Nor can added thin rubber help stop an underinflated tyre's bead from walking across; what is fighting that is air pressure. If the tube retains its integrity in this situation (a big 'if' given the chopping/pinching actions it's subjected to and the likelihood that it being already ruptured is the cause of deflation) then it might retain some air that would otherwise possibly be lost if the bead briefly breaks seal as it wriggles across to the well. So, that is a possible, though not probable, & quite minor "plus". It's the only one though & is well outweighed by the probability of tube failure & rapid loss of air caused by chafing. Without the tube, remember, one has the valve hole blocked by a tubeless valve. When a tube is breached (by chafing in this scenario) air loss is rapid via the the hole (as Avon note).


    or multi-piece wheels.
    Maybe. much depends on the sealing achieved on assembly. Not relevant with Renault wheels anyway & the rivets seem not to be problematic (if an issue, then "goop" them).

    Where tubeless tyres are fitted with wire spoked wheels where air could otherwise escape through the spoke holes in the wheel.
    Inner tubes should not be used as a means of repairing a puncture to a tubeless tyre, as a proper repair should be carried out to retain the tubeless properties of the tyre.
    The fitment of tubes to tyres of 65 series and lower is not recommended.
    If correct size tubes are not available, an alternative size tube should NOT be used.
    Wire wheels, multi-piece wheels and some single piece wheels designed for tube type applications CANNOT be used as tubeless fitments and the use of a tube (regardless of whether the tyre is “tube type” or “tubeless”) is ESSENTIAL FOR SAFETY. Always use tubes in such fitments.

    Wire wheels are, indeed, impossible to seal. Multi-piece wheels? maybe; it depends on sealing. Normal tube tyre rims? I have argued above why there is not an issue. Avon gives no argument why there is (purportedly) an issue. Closest to one is the quick mention of wheel safety ridges but, as explained above, they are causally neutral until severe deflation & tubes don't help anyway. "

    cheers! Peter
    Last edited by 4cvg; 25th September 2015 at 01:50 AM.

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    I'm still trying to work out what on Earth Avon thinks is the issue with tubeless tyres on non-ridged wheels. Perhaps that the link is from Avon Motorsport is the key.

    I can think of one scenario (much more likely in a competition situation than even very fast road driving) where a tube might help even if the tyres are fully inflated to specification.

    Consider the situation of whacking the tyre (not the wheel) with considerable lateral force (say, belting into a curb in a slide). Say the force is sufficient to move the bead into the well or, at least, briefly distort it enough to break the seal or, perhaps, to tear the sidewall. With a tubeless tyre, each scenario will result in some degree of air loss (major if the bead gets into the well). With a tube fitted, and assuming it isn't ruptured in the event, the air loss is prevented. Mind you, with the bead in the well, the tube won't last long. Still, an advantage if it lasts long enough for the immediate drama of the event to be over.

    I must say that even with my Djet (of my toys, the one that spends the most time at various angles to the line of travel & the only one I deliberately 4-wheel drift on occasion) I consider these scenarios to be sufficiently unlikely in fast road driving to weigh minimally in the equation compared to the disadvantages of a tube. The Djet's wheels (reversed R16TX) are, incidentally, not ridged & its tyres are tubeless.

    In the case of a Renault 4x15 wheel, the considerations are even more in favour of tubeless 145/65 on these wheels. First, as Avon rightly note, tubes are inapt for 65 profile tyres or less (the tube is circular in section & the tyre is roughly elliptical - a recipe for heat generation & chafing, possibly pinching). So, if one wants 145/65, then it's tubeless or not fitting the tyres at all.

    And one should want them, if only for the safety improvement under wet braking on the front wheels. One's chances of an emergency stop in the wet are greater than sliding & whacking a curb or whatever. And the Contis are indeed good wet brakers. They were test winners back in their prime (around ten years ago) & even if that is a while back, that record is not one rivaled by the rather dire alternative fitments for these wheels. I use 145/65-15s as spares on the Djet, R8 & 4CVG. A while ago, I fitted two of them to the front of my R8 (with the 165/65-14 normal front tyres moved to the rear) while some new rear wheels were being made up. Predictably, I played around in the wet & provoked them under both over-swift turn-in (to provoke grip loss at the front) & sudden braking. I was impressed. Overall limits were lower than the R8's normal 165/65-14 EcoContact3 tyres (the type that generally replaced the EcoContactEP) but limit behaviour & recovery were good & in outright grip, they were not frighteningly inferior. ZX & XZX Michelins, Nankangs, Firestone F560s, Vredesteins & so on would have been just that.

    Perhaps someone can do a better job of understanding Avon's strange remarks but I have already voted with my feet (or tyres) against them.

    cheers! Peter

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    Just a small update on the Avon puzzle.

    I have been in extended technical correspondence with Avon Tyres Motorsport concerning my puzzlement at their seeming blanket condemnation of fitting tubeless tyres to rims designed with tube-type tyres in mind.

    Briefly put, their concern is that of having a possible slow leak from a non-airtight tyre/rim system (say, a bent rim). That's it; nothing else.

    They allow that all is, as I thought, fine if one has an airtight system & that no danger is involved until pressures become low enough (very low) to risk the bead "walking" into the wheel well. However, in a public document, they err on the side of safety in the advice they promulgate. (As I have remarked before, if you don't notice such low pressure in a R.E.R., I'd be astounded - & you should be embarrassed.)

    In short, what I originally said stands: fit tubeless 145/65-15 Continental EcoContact EP tubeless tyres (without tubes) to your standard 4 x 15 Renault wheels of any sort (spider or 3-stud) & you'll have considerably improved performance without any technical issues as to safety arising from that fitment. Just do check that you have an airtight wheel/tyre system &, if not, remediate that as I earlier outlined. And do attend to pressures (although they have to be direly low before the bead "walks").

    I am very glad to have had the circumstances of their misleading & strange-seeming advice clarified by them as the benefits of the fitment are sufficiently great for it to be regrettable if anyone had lingering concerns caused by their unfortunately sweeping turn of phrase.

    And: the reassurance has come in time for advantage to be taken of Continental's "4 for the price of 3" deal (expires end October).

    cheers! Peter

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    I'm doing some investigation on the rims for R8 and R10 as it seems most European makes had adopted tubeless wheels (naturally capable of using tubes and tube-type tyres) in the mid '60s. I would be surprised if Renault hadn't adopted this technology as quick as everyone else. I am looking through a spec book of my dads and found some reference to this but will read through it again to clarify. I should take a picture and post it so others can see.

    Edit: Just to clarify tubeless tyre capable rims are different to safety rims which were introduced later to incorporate humps that prevented the bead of the tyre from going too far inside.
    Last edited by minigordini; 21st October 2015 at 09:21 PM.

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    I think that you'll find that the difference is a slight slope angle difference in the part of the rim where the bead seats. I think that you'll also find that it's not an issue in any post war rim (including Renault spider wheels). Again, the issue is pressure. Even under high cornering loads there isn't bead migration unless the tyre is severely under-inflated & that degree of under-inflation is very obvious on a rear-engined Renault.

    That said, I'll be very interested to see what you come up with.

    To repeat an earlier comment: I find it bizarre to be worried about a tubeless tyre peeling off because one hasn't noticed that it's running on 7psi & thus refusing to fit a tyre which is vastly safer in performance. Rather than fitting wet-gripless Nankangs or Michelin ZX & exacerbating the tendency of these vehicles to enter the accident frontwards under wet braking or with a front corner or rear corner depending on which end snaps in an emergency avoidance manoeuvre, one could ameliorate these faults with a rather good tyre. For those who enjoy driving these cars briskly, the fitment increases that enjoyment (crisper response, better grip everywhere & more benign limit behaviour) while retaining standard rims. I just don't get why anyone would hesitate.

    cheers! Peter

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    This is what I found. It is from a book that talks about cars to 1980 but doesn't actually include R8 and R10. It does have R12.

    I don't have access to any R8 or R10 rims but it seems if the rim numbers include FH at the end it is designed to be able to use tubeless tyres.

    tyres for 4 x 15 wheels-renault-1980-cover.jpgtyres for 4 x 15 wheels-renault-rims.jpg

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    Quote Originally Posted by minigordini View Post
    This is what I found. It is from a book that talks about cars to 1980 but doesn't actually include R8 and R10. It does have R12.

    I don't have access to any R8 or R10 rims but it seems if the rim numbers include FH at the end it is designed to be able to use tubeless tyres.

    Click image for larger version. 

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    Yep, but I don't think that you'll find that level of detail stamped on the rim. Anyway, FH or not, fit away. To repeat again, there is no issue unless the tyre is severely underinflated.

    cheers! Peter

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