I got my bike out of the car after yesterday'e Etape and was shocked at the state of my front tyre.

A 23mm Conti 4000s. I've ridden about a 1000 or so miles on it. But its perishing between the sidewall and the tread. A bit freaky when I saw 44mph on the Schiehallion descent.

How long should a tyre last? Should I deflate it when in storage? Any other light/durable tyres I should be looking at?

Deflate when in storage and the contis should be fine.

http://www.conti-tyres.co.uk/conticycle/technical_safety.shtml

"Tyre Maintenance
Take some simple steps to ensure you get the best possible life out of your Continental tyres.

Sunlight – Tyres do not respond well to prolonged sunlight (ultra violet) exposure. The tyre rubber will become weak and will eventually crack and break up. Store your cycle away from direct sunlight when possible.

Damp – Damp storage conditions will also shorten your tyres life. If you’ve been out in the rain, make sure your bike is left in a dry atmosphere immediately following your ride.

Not using the bike for a while? Store the bike upside down, or hang it up to prevent tyre deformation.

Inspection – Inspect your tyres before every ride. Check for cuts and wear & brush off any road debris attached to the tread.

Most importantly – Tyre pressure. Inflate your tyres to the recommended pressure in this guide. Carrying a heavy load? If so, then increase the pressure up to and including the maximum shown in this guide. "

Deflate when in storage and the contis should be fine.

Really? That'd be the last thing I'd do, I'd always keep them topped up to avoid perishing.

So in summary, don't go out if it's sunny or if it's raining 😆

I fitted the tyres new last September for a couple of weeks ride in Orgeon. I rode perhaps 600 miles. The sun shone every day. Since then they've been stored in a dark cool garage. I've done around another 4-500 miles here in Scotland since. I tend to leave them inflated to about 90 psi, but they lose a bit bit in storage.

I checked their condition before the ride, they looked fine. I really was shocked at their condition when I got back.

So, what other tyres should I be looking at as a replacement?

I've had a conti perishing quickly before.

Have never understood (nor seen evidence to support) the deflation myth either – didn't that come from tub mythology?

Deflation would surely just lead to extra strain on the rubber and increased likelyhood of cracking. Keep them dry and in the dark and they last for years, I've got some ritchey megabites that are still happy in storage – how old must they be?!

the conti GP series are known for cracking quite quickly. They also wear very fast. That's the price you pay for excellent (wet weather) grip

I'm not buying Conti again. The others I've used have perished at higher mileages, but for a front tyre to go after little more than three weeks riding, thats no use to me.

Michelin? Specialized?

Natural rubber does give good grip but also perishes easily.
Sometimes ozone is blamed for rubber perishing.