Folding Bikes - best tires for Air Friday with Sun CR18 rims

I am taking my AF to Europe in September where I know (from hard experience) that spare 20" tires and tubes are hard to find.
I want to be prepared with a pair of spare tires and about a dozen spare tubes.

I'd like to know the best tire size choice for this bike. I am confused between 406 and 451.
(I currently have 451 Stelvios on my CR18 rims. But I am not sure those are the original spec for the bike - I am inquiring of Green Gear.)

Can anyone guide me?

I am taking my AF to Europe in September where I know (from hard experience) that spare 20" tires and tubes are hard to find.
I want to be prepared with a pair of spare tires and about a dozen spare tubes.

I'd like to know the best tire size choice for this bike. I am confused between 406 and 451.
(I currently have 451 Stelvios on my CR18 rims. But I am not sure those are the original spec for the bike - I am inquiring of Green Gear.)

Can anyone guide me?

I'm pretty sure that the bike can fit any 451 tire. The only think that might limit tire selection is the caliper brakes.

You can't switch from 451 to 406 without a ton of work. And I'm not sure that you could do it anyway.

I'm not positive, but I think that the only folding tire in 451 -- since you're going to use these as spares -- is a Schwalbe Durano which replaced the Stelvio. The "best" tire for the bike depends on your preference. I like wider tires which would push me to Primo Comet 20 x 1 3/8" tires.

There is the Panaracer Minits lite too. 451 and folding.
http://www.panaracer.com/urban.php#minits_lite

I am confused between 406 and 451.
I currently have 451 Stelvios on my CR18 rims.

406 is a different, more common, BMX wheel size , but yours are not those.
rim size, diameter , is what those numbers mean..

You have a bigger diameter rim and a thinner tire is what goes with that.

more of what you have , the stelvio s not handy?

As others have replied, 451 and 406 are not interchangeable. See Sheldon Brown's web page (http://sheldonbrown.com/tire-sizing.html) on tire size designations for more details. In short, 406 is also known as 20"x1.5" to 20"x2.125" (decimal inch sizing), while 451 is also known as 20"x1-1/8", 20"x1-1/4" or 20"x1-3/8" (fractional inch sizing).

There are inner tubes sold as being compatible with both 406 and 451 (e.g., Continental), but I find them much more difficult to use with 451 rims and tires. They are smaller in diameter and so harder to mount on the rim, and they also make it harder to seat the tire bead on the rim.

As for more alternatives to Stelvios, there's the Schwalbe Ultremo ZX (451x23mm, 160 psi), but it's very expensive (street price over $75, last time I Googled). I've used Duranos and Panaracer Minits Lites satisfactorily, but I don't do loaded touring.

Schwalbe is a German company, so European based, and you are going to Europe..

Though the walk-in may not have a tire in stock , like here ,
shops can get orders filled from distribution warehouses, in a week..

Yes, more Stelvios are handy but not having studied this 20" tire question much (preferring to just ride) I was considering a switch to 23-451 Kenda Kontenders (which interestingly enough I found available on a wheelchair supply website - who knew?)

But reading up here it seems that skinny tires on small diam rims is a false match.

I don't quite understand why, but will read up more.

Schwalbe is a German company, so European based, and you are going to Europe..

Though the walk-in may not have a tire in stock , like here ,
shops can get orders filled from distribution warehouses, in a week..

I need to have spares instantly on hand in case of a blowout during my 4 day trek. No time to wait a week for delivery. That would kind of blow the vacation. I can afford 15 minutes downtime for a change, not a week.

Yes, more Stelvios are handy but not having studied this 20" tire question much (preferring to just ride) I was considering a switch to 23-451 Kenda Kontenders (which interestingly enough I found available on a wheelchair supply website - who knew?)

But reading up here it seems that skinny tires on small diam rims is a false match.

I don't quite understand why, but will read up more.

I don't agree that skinny tires on small diameter rims is a false match. I use Continental Gran Prix on my Air. However, if you are contemplating touring, you may want to consider a wider tire.

I need to have spares instantly on hand in case of a blowout during my 4 day trek. No time to wait a week for delivery

fit 2 on the rims, bring 2 spares.. easy peasy.. they hide in the luggage easily..

Your current Stelvios are 28mm (1 1/8") width (451 mm rim bead seat). Other tires of that width and diameter are made by Kenda, IRC (Roadlite), and Primo (Comet). I've used both the IRC Roadlite and Primo Comet on my Bike Friday Pocket Rocket and haven't had any issues with either. Neither has a folding bead, but I just do the usual 3-loop arrangement to make them small enough to fit in one of the little outer pockets on my panniers. Currently I have the 28mm wide IRC Roadlite on the front and a wider version (~34mm) of the Primo Comet on the rear wheel where most of the weight is carried. Compared to a 700c wheel, the contact patch on the smaller 451 wheel will be shorter and wider - so it makes sense to use a slightly wider tire than you might be used to on a bike with 700c wheels.