Is it safe to use my tyres?

My '07 Ford Expedition EL was standing unused for 3 years before I bought it last month with 13 miles on the clock. For at least the last year it was stood uncovered in the desert (in summertime heat of up to 115+ degrees). Before that it may have been in covered storage or out in the open, I don't know.

Everyone (except a local tyre fitter, but I don't know how qualified he is) has advised me to change the tyres (which are Pirelli Scorpions), but they seem in good condition and I have driven 2,000 miles so far with them on. However, next weekend we're planning a 1,000 mile trip through some of the most desolate desert known to man in 100 degree heat and the last thing I want is a blow out on the highway. BUT I've got a bit of a funding crisis at the moment and I can do without spending the equivalent of US$900 on tyres.

So do I risk it and run on the current shoes, or do I play it safe and invest in some new ones? Does anyone have any experience in this?

TIA

Recent bulletins from the tire industry indicate that tires degrade simply due to time. The age of a tire is important even if the tire is unused. There some disagreement over how to best express this age limitation, but my take is:

If you live in a hot climate (AZ, CA, NV, TX, and FL) then the limit is six years. If you live in a cold climate (MN, ND, WI, MT, etc), then the limit is 10 years. States in between are ..... ah ........ in between.

The fact that you spell the word with a "Y" says you are not in the US (So does the +115°F) These are about the most extreme conditions on the planet.

To be safe, you should replace them. What you do not want is for a tire to come apart at speed - very dangerous.

The fact that you spell the word with a "Y" says you are not in the US (So does the +115°F) These are about the most extreme conditions on the planet..
He's in Saudi Arabia.

Does everyone in Saudi Arabia change their tires when they are 3 years old? Sure, SA is a harsh climate for tires, but I expect the average driver gets more than 3 years out of a tire.

IMHO there is no reason for the OP to change the tires, unless there are obvious signs of trauma, such as cuts, bad cracks, abnormal bulges, vibrations when driving, etc.

Thanks for both angles of advice; I have gone down the middle way.

I chose to replace them with a new set of Continental Contitraks (and only afterwards saw how bad they fared in Tirerack's surveys/reviews!). However, I also got the garage to drop the old tyres round to my house because I reckon they're still OK for a few thousand miles of city driving. So when I get back from my weekend trip I'll put the originals back on and keep the Contis for when I need them again. Tyres cost so much out here (yes, I am in Saudi Arabia and my Continentals were the equivalent of US$ 215 each) that you need to squeeze every mile out of them!