I purchased two identical HD Gravity bikes. They came with lower end 2.1 tires. We have a bunch of sand on our trails here in Florida so I upgraded the tires to 2.3 WTB Breakouts. This is the biggest tire that can be placed on that frame. One bike is great with this tire. It performs very well. Fun to ride with the extra grip. The other bike has a bad tire rub on the back. The tire can't be centered on the frame. I remounted the 2.1 and noticed it is not centered either. I never noticed right out of the box because it never rubbed. Customer service was no help. So, long story short, my experience was 50 % good and 50% bad. Now I have one bike I really like and one I don't. They are for my wife and I so I make sure she has the one with the most grip.