18 vs 20 in rears

there is no reason for 18's if you ride trails....

18's are for MX. I would go with the 20's

i agree. i run 18's, but i mostly do mx style riding. if your just gonna be on the trails, get 20's. the 20's will work better on the trails, and you'll still be able to play around on the mx track
 
where i was riding the other day, i don't think that 22s would've been any better than the 18's, the ruts and washouts were so deep that you had to just choose your line pretty carefully and go with it, the only times i had bad troubles, i would've had with any reasonable sized tire
 
ya dont get 18's om runnin 22's i think they look to big but there is soo much ground clearence they r for trails on really but hell if any one wanna trade ill trade for some 20's lmao
 
If I had a higher powered machine, 6ply 20"s are they way to go for trails. Perfect medium.

But I can get around just fine with 18"s on my little blaster, I love the lower seat height and the less rotational mass really helps keeps the wheels spinning and keep it pinned.

I have a few problems, one gearing. even with 14/40 sprockets 18"s just don't have enough top-end and I feel gearing it any higher (sprocket wise) would make it a turd (my bikes pretty stock)
Two tire life.
Three winter time.
four the occasional trail that I just don't have enough clearance for. But usually I can just pin it and go over, I only have a problem if I'm going slow lol.

I do have some 22x12x10 swappers if I need them, but I never do.
Riding with bigass tires feels like I'm riding a tractor and I hate that.
Plus smaller tires look so much better (but thats pretty much my opinion and doesn't mean a thing)

Ultimately if your unsure get 20"s, those are a great medium for everything.
 
I ride trail all the time. I have 22's on my '01 blaster. I like it for the clearance and gear travel. I also have a pair of 18's for MX. 18's are way to small for trail in my opinion. They are smoother riding but they're too low and brush and stuff just drags, or gets caught in your chain. I'd go with the bigger tire, 20's are what I'm getting next because they are in the sweet spot of clearance and gear travel.