looking at maxxis advantage kevlar tyre for my rear wheel..
can someone explain the following :

2.1″ Kevlar 70a 60tpi
2.1″ Kevlar 62a 120tpi eXCeption
2.25″ Kevlar 60a 60tpi
2.1″ Kevlar UST 120tpi

ill have a go…

1.70a – harder wearing, faster rolling, less grip ,60 tpi threads per inch = durability… i think

2. 62a – softer compound = more grip but faster tread wear, exception = lighter but thinner sidewalls= easily damaged on sharp rocks

3.60a – even more grip but even faster tread wear

4. UST = tubeless for specific rims = no need for innertube

right thats my ten penneth….. how did i do?

size, bead material, compound hardness (not ust, that means it’s for tubeless ust wheels), threads per square inch i.e. quality. more = better.

2.1″ is big for a 2.1″ (very almost as big as a 2.35″ High Roller/Minion)
2.25″ is very big for a 2.25″ (I reckon ever so slightly bigger than a 2.5″ High Roller/Minion, lower tread/inner volume is slightly bigger anyway)
Because they’re so big ‘normal’ tubes aren’t anywhere big enough IME. The first 20psi pumping up is stretching the tube to fit the tyre, I found I needed 50psi + to stop them pinchflatting all the time
Maxxis 1.2mm freeride tubes work well with them.
Because of the round profile and ‘not as big as high roller’ side tread they don’t seem to corner well up front without running at noticably (while ridig) low pressures

70a – hardest compound, cheaper, longer lasting, fastest rolling, least grip
62a eXception – claimed to roll (nearly?) as well as 70a, and grip (nearly?) as well as 60a, quite expensive, lighter, only available in 120tpi. I’m not sure on lifespan
60a MaxxPro – medium rolling/grip/lifespan/cost. though can be a bit draggy for ‘XC’.

2.1″ Kevlar 70a 60tpi – 640g for kevlar/folding
2.1″ Kevlar 62a 120tpi eXCeption – 595g
2.25″ Kevlar 60a 60tpi – 660/700g depending on source (of claimed weight, though it may be newer versions are beefed up a little, as original ones were pretty thin)