Dunlop Special Lightweight rims - Tubs or Clincher?

A question for some of the vintage experts on here.
I picked up a pair of 27" Dunlop Special Lightweight 32 and 40h rims a while back and I have noticed that they have a very shallow profile not quite as shallow as a tubular rim but not as deep or with noticeable hooks for clincher tyres?

Does anyone know if I can fit clincher tyres to these rims? Specifically the Panaracer Pasela 27" x 1" clincher?

cheers

if there are no hooks/lips, i doubt a clincher will stay on

A picture of the OUTSIDE of the rim (where the tyre is seated) is what is required, instead of the picture you have offered.

Old style clinchers did seat differently to modern ones. The rims were less "lipped" also.

They're not clincher or tubs, clincher or hook/bead rims came in in the late 50s, you can fit a beaded tire to these but you won't be able to use much inflation pressure, if you're lucky maybe 40 or 50 PSI.
If you use more pressure the tire will unseat, nice rims by the way...

A picture of the OUTSIDE of the rim (where the tyre is seated) is what is required, instead of the picture you have offered.

Old style clinchers did seat differently to modern ones. The rims were less "lipped" also.

Yes, not the most descriptive image, only one I have to hand at the moment. These rims are definitely less "lipped"

They're not clincher or tubs, clincher or hook/bead rims came in in the late 50s, you can fit a beaded tire to these but you won't be able to use much inflation pressure, if you're lucky maybe 40 or 50 PSI.
If you use more pressure the tire will unseat, nice rims by the way...

Right, so what kind of tyre would of been used with these rims to get a higher PSI? And can you still get them?

Right, so what kind of tyre would of been used with these rims to get a higher PSI?

There is no tyre which will allow very high pressures on old Dunlop/Endrick/van Schothorst rims. The whole point of modern hooked bead or* crochet *rims was to get over the problem of tyres blowing off the old style rims at high pressure.

I have these rims as well, for a current project. I am advised that they are for clinchers, but you need to run a lower pressure than that stated on a modern tyre. This means you may need a wider tyre (ie 1 1/4") to cope with the lower pressure.

I bought my rims from an authority on vintage bikes and he advised
"All Dunlop SS rims are for what were called wired-on tyres...what are now
frequently called clinchers. There are no SS rims for tubs. Although
Dunlop used to make a full range of tubs they never made any rims for
them."

In the olden days, even racing tyres used to come with two pressures marked on the side, one for "normal" rims and one for hooked bead rims. Now they just say "Use only on hooked bead rim", leaving you to guess what pressure to use if you fancy trying them on old rims. I would be on the lookout for a tyre which works well at 40psi or so. Schwalbe do their HS159 in a gumwall colorway™, which I assume is what you're after for anaesthetic™ effect, with a suggested pressure of 50-85psi, so they should work at 40 if you're not a total lard arse.

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Thanks for that Bigblock,

So does that mean that the 27 x 1 inch panaracers that I have might be too narrow, would 1 1/4 make that much difference?

What kind of psi are you going to run? Is 40-50 to low?

tyre pressures are chosen to achieve a suitable 'tyre drop' based on the weight of rider and bike.
I use this article to to set my road bike pressures.
You can see from that chart going from a 1" to a 1 1/4" means the tyre pressure can drop substantially for the same loading.
I am asking on a retro forum for their input. I will report back.

The answer I got back is below. To put in context, the reply is from an Pom, now resident in Australia

[INDENT]il padrone wrote:In the 70s, before the hook-bead rims came along a high pressure clincher was 80-90 psi.
In the 50s......? Maybe 70 psi, I don't know.
[/INDENT]Have to agree with Il Padrone (getting to be a habit - worrying.... ) Back home we used to run our Michelin on 'plain' Weinmann rims at a max of 90 psi on the tandem. In summer you were careful not to leave the bike in the sun for any period at this pressure or you risked a blow-off . Also heavy braking on long downhills on a tandem could heat the wheel up to the extent you blew off the front tyre (reason for rear drums....).
I wasn't around in the 50's but the old guys in our group who were used to run 80-90psi in the tyres on their Dunlops. However they did say that clincher tyre quality had improved so much between 1955 and 1975 and that they wouldn't have risked that pressure using the tyres available then. I didn't bother at the time finding out what that pressure was.
Also, I used to commute to work in London on an old Raleigh 'racer' which had these rims and in my ignorance I ran them at 80psi with Michelin World Tours and had no problems (of that sort) at all.
I wouldn't put a folding tyre on an unhooked rim mind you, that's asking for trouble
Sheldon Brown also advised

Traditional 630 mm (27 inch) rims were straight side design, but in the late '70s they evolved to a "hook edge" design which would permit the use of higher pressures. These days, many 630 mm (27 inch) tires are marked "For hook edge rims only" (some companies use the term "crochet type" instead of "hook edge"...this is the result of poor translation.)
The fact is that modern 630 mm (27 inch) tires will work on older straight-side rims, but they won't handle as much pressure as they are capable of with hook edge rims.
Generally, the "rule of thumb" for traditional 630 mm (27 inch) tires is that they should be inflated to 70-75 psi. This shouldn't be a problem with any tire, despite whatever disclaimer the manufacturer puts on the sidewall. However, if you're restricted to this pressure range, you probably shouldn't be running tires narrower than 1 1/8, or preferably 1 1/4, unless you're a very lightweight rider.

on that page there are also the measured widths and there appears to be substantial variariations the the actual widths (needed for calculating the tyre pressures based on tyre drop).
So I will be buying some rigid (ie non-folding) 27x1 1/4" tyres.

Thanks for that Bigblock, all very informative. Sounds like I'll need to get some slightly wider tyres.

from the C T C's Tyres Q&A

High pressures call for hooks – 2001.01
[INDENT]I was recently looking for a 27 x 11/4 cover and I noticed on a Continental Top Touring the moulded instruction "use only with hooked rims". I have another which appears identical but does not carry the instruction. Do you know if there are in fact differences in construction between them, and what are the implications of ignoring the instruction? John Arthur, Middlesbrough

[/INDENT]A spate of similar emails led me to research this issue. Generally: any rigid steel-beaded(non folding) tyre that does not call for more than 5bar (70psi) can safely be used with straight sided rims. With higher pressures however, or the flexible beads of folding tyres, the bead stretches away from the bead-seat and hooked rim edges may be needed to stop it lifting too far in one place and blowing off. Continental are especially keen to ensure this does not happen, so they not only make their tyres a close fit but also mark "use only with hooked rims" on any with a higher than 5 bar maximum pressure. All modern rims are hooked so it’s seldom an issue. However the market for the 630 (27×1¼) size concerns older bicycles and rims mostly without hooks.
Talking about 32mm (1¼ inch) section tyres: the original Top-Touring was rated up to 5.0 bar and had no such warning. When the Top-Touring 2000 was introduced Continental rated this slightly higher and also boosted the Original to 5.5 bar (75psi). This took both tyres into the “hooks only” category, along with the 32-630 (27×1¼), 5.5 bar version of the Sport 1000. Possibly this change came from a slight improvement in casing strength. Or maybe (since consumers often associate higher pressure with higher quality) they simply asked how high can we make it? I can’t see any difference in the design. Certainly all three still have steel beads so I reckon they should be safe enough on old-fashioned straight sided rims provided you don’t inflate over 5 bar. John Arthur has followed this advice with no problems on his Conti Top-Touring tyres. However some alternative makes – marked with higher maximum pressures and no other restrictions – have been reported to blow off old 27 inch Weinmann straight-sided rims even when carefully inflated below 5 bar. So it appears some other manufacturers are keener for your custom than your safety. and hooks call for high pressures

On the other hand some riders report severe problems with Continental touring tyres on the designated type of rim! In some circumstances the hooked edge can bite through the casing, resulting in sudden and unpredictable deflation! These circumstances seem to involve two or more of the following factors: too low inflation pressure (note: high-pressure tyres need pumping at least once a week); a heavy rider (tandemists have worst problems); rim with sharper than average hook or prominent extrusion die-lines; rim where previous chafing has roughened the hook.
Such failures are not exclusive to Continental. According to member feedback it seems most other makes of tyre are more or less vulnerable. It may simply be that high-mileage riders are especially drawn to Continental tyres by their puncture resistant and durable treads, that nonetheless roll very well. All I can suggest is to smooth the “biting edges” of hooked rims (e.g. with emery paper) – then pump the tyres good and hard and often. Chris Juden

sorry to resurrect an old thread but I have one of these wheels laced to a 32 hole raleigh hub with oiler, would anybody know its worth, I have someone who wishes to buy it but I have no idea what to ask, I've seen silly money for the 2 rims on ebay, I just want a realistic estimate as I know I may need this wheel in the future so might be a bit silly to sell it!

Hi all - just joined the "club". The pix of the Dunlop rims got me going. I have a 1951 Raleigh Clubman that I just finished a mechanical restoration. This bike is a dream to ride. I'm working on an update lighting system. I have a number of the old SA Dynohubs, and I bought one of those small sport lights. I built a full-wave rectifier to run an LED in the headlight. Now I'm looking for another rim to lace the hub into. Anyone wanna sell me a front 32H rim? As for tyres, I have the original Dunlop rims on my bike and I bought some cheapo 27 x 1-1/4" whitewalls by Duro on eBay. I typically put 90 PSI in them and run around all day. I hope i'm not taking my life in my hands!!