Woody would know your best options. Those are real dirtbike sizes. Can you get a 908 to fit that rear? I'm only familiar with the 150 size 908 for the KTM twins.
Regarding what to start with, we'll have lots of dirt Tuesday, Wed, Thursday and Friday. This includes the Blackwater (mild but fun farm road); the Kispiox forest service roads (I think) past the K'san village (was rough in 2006), Telegraph Creek, and North Canol to NWT camp (135 miles in) and back again Friday morning. These will be trip highlight rides of the event, so you want your favorite dual sport tires for them. If you wanted a more durable street oriented tire in back, I would try to get as far as Fairbanks before changing to it. After Fairbanks we'll only have the Denali Highway, which was rough and slow in 06; and fast and smooth in 10. Any rear would work fine and it's only 135 miles end to end.
I used Conti TKC 80's front and rear in 2006 on a KTM 950. This was an excellent tire in the mud we experienced, and fair on tar. The rear would slip on cold/wet lane paint. Nothing scary but enough to pay attention. My rear probably could have made it to Fairbanks, but I changed it in Dawson. The front went paper thin on the way back and I ended up changing it in a motel lot south of Watson Lake. Probably not a mile too soon.
While at Fairbanks we will have a one day blast to the Arctic Circle and back. I've never ridden the Haul Road, but the Dempster had plenty of mud and was fairly flowing through the ranges. I think the Haul road is better maintained, straighter, and more heavily traveled so probably a street oriented rear would be fair.
I hear the Dunlop 908 lasts longer than the TKC80, but you might be looking at a 606 with the rims you are planning.
I'm planning on using Pirelli MT21's on my 690. I can get 3500 miles out of the rear if I'm careful and air it up for the long tar sections. If I ride the 250, I'll use Michelin T63's. I have considerable all-terrain experience with both tires on those bikes, but I'll need a second set front and rear no matter what I ride.
The main thing IMO is to have a good knobby front tire.
Originally Posted by sailah
Thanks I was wondering about actual tires too, I have used the dunlop 908rr with success and probably would use that with a good dot knob front. You think more street ish tire to start and more knob to finish off?
I'm getting the rear in a 2.50" rim width I think. It's a dirt bike rear end so I can't go too wide. Front will be a 1.60" excel a60. I have a 2.15" on there now in the rear.
Glad to hear about the rotopax I've based a lot on my build to using one