Is there a maximum age of tyre you'd consider fitting to a vehicle?
I'm looking at buying 4 new tyres, and they've been reduced (I believe) due to the DOT date being in 2012.
Is there any problems fitting (potentially) nearly 3 year old tyres?
You should not have any issues with these tires when you are comparing the "birth date" of the tire. There are two reasons I say this:
First, two plus years really isn't that old. TireRack.com has this on their website about it -
Our experience has been that when properly stored and cared for, most street tires have a useful life in service of between six to ten years. And while part of that time is spent as the tire travels from the manufacturing plant to the manufacturer's distribution center, to the retailer and to you, the remainder is the time it spends on your vehicle.
Second, should a place selling tires sell known bad product (in this case, tires which you think might be too old), they are liable for those tires. If they put tires on your car which they know have a chance of going bad shortly, you could easily come back to them and sue them for big money.
If the tire dealer is trying to get rid of older stock, this is the way I'd do it to. Get rid of the tire before it gets too old to sell. It will make them more money than throwing them away when they do get too old (being worth something is better than being worth nothing). A lot of tires have about a 35-40k mile life span on them. If you are running around 12k miles in a year, you'll wear these tires out prior to them being too old. My suggestion to you is, if the tires fit your car, you can afford them, and you need them, then buy them. Sounds like a win-win for you.
Tyre distributors and fitting shops in the UK run thier stock on a 'Just in time' basis. This means that when the tyre comes to be fitted you will rarely find them more than around 2 months old since manufacture. The UK recommendation is to replace tyres at no more than six years for an on the road tyre and ten years for a spare. This is rarely appreciated by vehicle owners on the basis of cost alone. Drivers will shrug thier shoulders when filling the fuel tank for £100, but burst into tears on the price of a tyre at £75. Poor tyres will use up to 20% of fuel put in the tank, as against a usual 15%. It is just common sense, even on a cost basis let alone safety, to have good quality tyres. Buy the best tyres of a premium brand for your vehicle un-fettered by the baggage of them being 'old'.