Caravan Tyres.

I wouldn't worry. You're not talking rocket science here.
But DO protect your spare from the sun with a cover (the ones available from this website are good.)
Or even tyre black from your local auto department helps a little with sun damage to the spare.
I would rather have a spare in as new condition on my van if ever I blow a tyre rather than one half worn.
Cheers

Alan,,,It sounds like you are talking about a single axle van,I would be interested to hear where on the tyres the wear is occuring. If it is on the inside and a smooth wear it may be the same problem as I have had with my van. As a mechanic I know a bit about tyre wear etc and with my van I noticed as stated above. The first thing I did was to get a tape measure and measure as best I could the distance between the top of the tyre compared with the bottom. This can be done by marking the centre of each tyre,rolling to the top measure, then roll to the bottom and measure again. This will give an indication of the wheels sitting square ie, equal top and bottom, In my case the bottom was about 5mm wider. In my van they have made the axle out of solid square with the ends turned down for the bearings,solid is not as strong as hollow and the axle had bent. I had to remove the axle,make up a rib with 40x12mm flat bar to clamp along the top problem solved nomore tyre wear. You may not have the same problem but thought I would mention how I solved mine as someone else may be having this problem.

Further to the above...
The biggest problem with 'van tyres most people have is underinflation.
Light truck radials have a rating in kilogrammes which ASSUMES MAX INFLATION PRESSURE>
ie: if you run them at say 40psi (from a max of say 65 psi) then you have to reduce your rated load accordingly. Many manufactirers recommend a tyre pressure which is actually too low!

Also, just for info, I have an 18 month old 'van on which I was getting uneven (and rapid) tyre wear. Trouble is I discovered the problem after it was out of warranty. Axle was very crooked- manufactured that way I suspect, by a well known (german) manufacturer! (It was hollow with stub axles welded in each end.)
I tried to get some joy with them and the van manufacturer but got nowhere- had a new (stronger) solid axle made up locally for $115 which was easier than fighting a large corporation!!!!
Meanwhile I'm keeping my spare "as new" by keeping it protected from the sun etc!
Hope this helps- Cheers