Originally Posted by
Herzlos
They'll eventually burst when you wear through the tread, but if you're on a trainer that holds the bike by the axle you'll be fine.
I'm not sure I'd use them on a roller, but then I can barely stay on a roller anyway.
Many people define "old tires" as slightly squared off but no where near worn out. Old and worn out tires are exactly what I use on the rollers and I've never (in 50 years) had one "burst." Without the rough surface of the road, they last forever. And regards the OP's question, a typical trainer might wear out tires faster than the road, but you have nothing to lose by putting your old tires on for that use. The only potential problem is if the rubber has hardened with age and is too slippery to properly grab the trainer roller.