I'm assuming it's new? Mine was pretty tight when brand new but loosened up a bit after it was on a while. Working with it after it's been in the sunlight for a bit helps a lot, too.

 

Better tight then loose. Just saying...

My new Bestop was tight too and near impossible to put on. I found latching the front the pulling down on the rear top bar and slipping in the plastic blades under the body hooks made it easer for the first few times until the top had some time to settle and stretch.

 

Let it sit in the sun for a while. I don't personally own a bestop top, but my seat covers were WAY tight when I got them. I let them soak in the sun for a while and they stretched out. I guess the same is true for most bestop products.

 

New tops are tight as a drum. Two hints... 1) let the top warm up in the sun before erecting/installing it. 2) The rear corners should be the last part of the top to be installed. Latch the front first by just inserting the hooks into the slots but don't close the clamps. Then install the rear corners, then close the front clamps all the way.