Like anything tyres have a finite lifespan, the shelf life of a tyre is around 4 years from manufacture but if you are riding regularly this will be much quicker!
You can check your tyres by simply looking at them. If the knobs are rounded down or short they aren’t going to perform very well. Knobs can actually crack and become ripped off completely so if you are missing any knobs you are up for a new set of tyres.
If you ride frequently this will occur quickly but if you only ride on the odd occasion (poor you) you will need to keep an eye on the health of the rubber. Over time the rubber will become dry, cracked or discoloured. New tyres have a very dark colour which fades out to a grey with age, the older the tyre the harder and more brittle the rubber becomes which will effect performance.