with manky on that one, ive got 16" rims with 45 profile tyres works out the same as 15"/50s, probably not as cushion like but i run with 10psi (or they may have not held and be flat i cant tell,WHOS IDEA WAS IT TO GET THESE F******G WHEELS) but 3rd is the man for getting going then 4th just to get the rpm down, ive never had a trike before, but have had ninja's and aprillia rsv millie's and personally i think the reliant trike is a nippy little thing 0-50mph certainly not to be laughed at and keeps up with any traffic, and if you stamp on the brakes it'll rip your spleen out