I'm on the GT Grade page on Facebook and the consensus seems to be 40/42mm is the ABSOLUTE maximum depending on rim width and that doesn't give much clearance. No way you'll get 2.1" to fit.
Thanks! I know the clearance on 700c/28" wheels as this is my second Grade, however I'm wondering what the tyre clearance would be if you fit 650b/27.5" wheels on a Grade, as the trend goes in adventure biking?
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\nMy guess is that it would probably be a bad idea, but I'm curious to hear if anyone has tried and what size of 650b/27.5" tyres may fit. Obviously wider than on 700c/28" wheels, but I think not wide enough not to lower the crank and mess up the handling.
By putting 650b wheels on you'll lower the bike by approx 14mm (622-584)/2. Putting 40mm tyres on will raise it again by approx 12mm (based on a rule of thumb that tyres are as tall as they are wide). So if there is enough width clearance where your 28mm tyres are for 40mm it might be worth a punt. (an expensive one though if you get it wrong). I've been thinking of doing the same thing myself but am waiting for someone else to try it first!
Check out the GT Grade page on Facebook, there are a couple threads on it. I think 650-42 is the limit in the rear and 44 is the limit in the front. Obviously that depends on tire wheel combo.
Just fitted a pair of Suomi/Nokian W240 40mm studded tyres, measuring 38mm in real width seated on original 700c wheels, under a pair of permanent mudguards/fenders (!), on my GT Grade X 2015. Very tight fit, but possible.
Quite happy with that, as the rough W240 would be my go-to tyre for harsh conditions, in addition to my fair weather 45nrth Xerxes 30mm.
Logically, there should be considerably more space with 650b/27.5". But then again, now maybe I don't need it.
