Seems to be a big difference in price between folding and steel bead (non folding) tyres. Folding are a bit lighter, is that the only difference?
Yep! 🙂
Depends which tyre you are looking at. Often better casing and rubber compound goes with the territory, but really it varies from one manufacturer to the other, as well as one model to the next.
You may have to get nerdy and look into rubber compounds and casings too. Perhaps the best/worst example of all these variable might be the 26" maxxis high roller. Because they make it for downhill as well as general mountain biking, it comes in four different casings, three or four different rubber compounds, five (yes 5!) dofferent widths, as well as folding and wire beads. Some wire maxxis tyres depending on the compound are grippier than folding ones (I have wire bead supertacky 45a wetscreams for example and for me this is a good thing despite the weight and wire bead), although undoubtedly folding, harder and slimmer ones are faster if you are also going uphill in a hurry.
Good answer julianwilson, didn't realise how complex it all was!
Did you have a particular tyre in mind?
If you are looking at the detail, on the casing, the higher TPI number the better. For rubber compound, the lower the number the grippier (but often slower and definitely less hard wearing) it is: dual compound with 60 or 70a in the middle and 45a on the shoulder/side knobs is great if you get the miles in. Some companies use names of compounds instead of numbers just to confuse further, eg schwalbe have pacestar (harder), trailstar (middly) and vertstar (well sticky) but you can usually google these to find out which are softer/harder.
just to point out that it is quite common for OEM tyres to not match the aftermarket equivalent.
You might hate the tyres that came on your bike, but if you actually had the aftermarket version fitted you might actually like them!!!