The success of the Moulton following its release in late 1962 left potential competitors with a problem; what to do about the bumpy ride that comes with small wheels. Naturally they wanted their own small wheelers to cash in on the craze, but they couldn't just copy the Moulton's suspension. They either had to design their own or do without.
So they did without. Their way around the problem was to fit 'balloon' tyres, which were 'fatter' than normal tyres and inflated to a lower pressure. These tyres soak up the bumps without the need for suspension. It was a novel idea for the UK perhaps, but not for the US, where such tyres had long been fitted to 'middleweight' bikes, transport for those too young to drive a car (or drink, or vote, but not to have a gun).
Besides the RSW, at least two other Moulton competitors, the first generation Trusty Spacemaster and the CWS Commuter, took the balloon tyre route. The tyres on these bikes were fat like those on their US brethren, but much, much smaller in diameter (even smaller than those of the Moulton). Raleigh advertising described the tyres as 'wide profile', to 'cushion the bumps and hug the road'.
Most of these tyres were of the 16 x 2 (305 x 54) size, but some were 16 x 2.125 (305 x 62). (I have read that the wider of these two was fitted to the earlier RSWs, but I can't confirm this.) They were made by Michelin and Dunlop, and some were 'Raleigh' branded. They were most commonly white, but black replacements were made by Michelin.
Of course, the elephant in the room when discussing these exclusive, shock aborbent tyres is their relatively high rolling resistance (which increases in inverse proportion to air pressure). With a maximum tyre pressure of only 35psi (compared to say, the usual 50 or 55psi in the 60s), RSWs have often been criticised for being slow. I think the makers would have been very conscious of the issue of rolling resistance, and (again, I can't confirm) they made the sidewalls especially flexible in order to minimise it.
When I ride a Raleigh RSW, I initially notice a high level of rolling resistance, but soon get used to it and forget about it. What's more, I don't mind, because the tyres are an integral part of a package designed to do a job, a job it does well. In other words, they suit the bike's limited purpose in life, such as going to the shops and other local trips. Anyone interested in fast riding or riding longer distances would choose some other type of bike anyway – no tyre can turn an RSW into a tourer or a sports bike. The white balloon tyres are a defining feature of these quirky bikes and well worth keeping. Think twice before choosing modern tyres for your RSW.
Raleigh RSW tyre replacement – some options
Schwalbe Big Apple
Modern tyre sold in various sizes. Like many modern tyres, they suffer from a surfeit of branding and those !#$%^ reflective stripes (which can be peeled off, with some effort).
Pros: Readily available. Probably more puncture resistant than the other options. Slightly less rolling resistance than original tyres.
Cons: Wrong colour; Ugly (branding, reflective tape); Harsh ride regardless of pressure; Looks a bit odd with large empty space in mudguard (because the tyre isn't as 'fat' as original); Bike sits lower (ditto), which could be a safety issue (I have used them on a Mark 2 RSW and CWS Commuter without problem); May (as on CWS Commuter) give the bike a slight 'dropsy' feeling, as if it wants to flop to one side or the other.
Made for the front wheel of the disconcertingly popular Raleigh Chopper kids bike. Any number of suppliers would be happy to sell you a pair. If you want an easy, cheap, hassle-free existence, these could be your best option.
Pros: Readily available; comfy; cheap. Slightly less rolling resistance than original tyres.
Cons: Wrong colour, red lines; Looks a bit odd with large empty space in mudguard (as per Schwalbe Big Apple above).
The ants pants. Get them if you can. Occasionally they show up on eBay.
Pros: They look right – preserves the bike's original appearance and character. Comfy. Bike sits at correct height.
Cons: Hard to get, costly. A bit more rolling resistance than the options above.
A surprising number of surviving bikes still have their original tyres in usable condition – after 50 years. Minor cracking is patina, not damage; ditto for age-related discolouring. Usable survivors should be treasured rather than tossed out.
Pros: As for NOS originals, but with patina.
Cons: As for NOS originals, except that you don't know what you're getting. You can never be sure of the condition until you've had a close look and tried them out, and you don't know how long they'll hold together. You may have to buy a bike as well just to get them!