Hey, I actually work in the tire industry, manufacturing on-road 18 wheeler tires and off-road tires for industry, mining and military. During the first Iraq war I converted an 18 wheeler tire machine to build tires for the Stryker LAV. It raised our production from 4 tires/hr to 14 tires/hr. Kind of fun getting paid to do mods. Given a team of guys and an unlimited budget and only two instructions: 1)Can you do it? 2)Do it NOW!
This however does not make me any sort of expert on ATV tires.
And certainly not an esthetics guru but I have some basic ideas about rear tires (correct me if I am wrong here):
Bigger tires (20-22) are good for ground clearance and floatation in rough terrain and mud, but trade off secure handling.
Gear ratio can be corrected with sprocketing, get the tires you need to do the job.
Low tires (18-19) really corner well but handle rough terrain. Better for flat and high traction.
Tread compounds matter. Harder terrain (rock & logs) needs softer rubber. Wears fast but it grips. Soft ground, sand, gravel and mud can use hard rubber.
Tread type matters. Chevron, paddle and fingers each have their own advantages. Where do you ride?
Tire pressure is hugely important. 3-5psi seems to work best with most of our tires. It is a fine balance finding the right pressure.
Tire weight does affect everything! Lighter is better as long as it doesn't puncture.
From these ideas, I figured I needed the ITP MudLites (not really light as sport quad tires go!) to get through rocks and mud and water, like this stuff:
The mud is deeper and softer than it looks and there are small trees cut off at an angle in the low brush that can puncture lighter tires than the ITP MudLites. The chevron tread worked well in the mud and water.
This sort of terrain below is kind of a sandy clay (or clayish sand?). Too hard for paddles and the chevron tread doesn't slide well. Small diameter tires with finger tread work well here.
About sand: Sand sucks horsepower. The chevron treads work well on it, but add a heavy tire end even my 40+hp feels taxed. The finger treads do not do well on sand and neither does a heavy tire. Sand needs light flexible tire, low air pressure and paddles.
These are my opinions.