On SibirskyExtreme, with my F650GS-D, I 'took over' a part worn rear Trelleborg from Kenichi, a UK Hubber we met in Irkutsk, and carried it to Mirny/Lensk where I put it on.
I am pretty sure it was the Army XT-644
The Plus points-
- its long, long life both on and off road. This tyre had ridden across Turkey and on to Irkutsk (Lake Baikal, eastern Siberia). At the changeover point it looked hardly worn when compared with the unused spare one Kenichi had been carrying.
I carried it to Lensk/Mirny where I put it on. It took me through the Viluysky Trakt to Irkutsk. Then the Kolyma Highway (Road of Bones) to Magadan - the fastest for this according to Wikipedia (Fame indeed!). This was all off road, mostly dry gravel/dirt.
After shipping to Vladivostock it took me on tarmac (cautiously!) to our Khabarovsk tyre drop where I had Metzler Karoos waiting. I left the Trelleborg with local bikers for anyone with a use for it. It still had some tread left - but not enough to even think about the BAM.
- soft or loose beading. I had a legendry number of flat tyres (I lost count at 15) but that was because I was still using the original BMW standard issue tubes. This tyre was the easiest I have ever known to get off and on the rim. The only 'tool' reqired to put it back on was my boot heel!
After getting heavy duty tubes at the tyre drop I only had one more flat all the way back to UK including both East and West sections of the BAM
- off road performance was as good as any other rear I have used on the bike. It gripped well on dirt, rocks and mud and very controllable in fast slides/drifts coming out of loose corners.
- low cost
Now the MINUS point, and a BIG one

-
- tarmac grip. UGH!
There was only about 300 metres of tarmac from putting it on in Mirny to where the dirt started. As we slowly rode out of town, twice on bends it failed to grip the dry tarmac, quite alarmingly. Although new to my bike it was not a case of new rubber - it had already ridden from Turkey to Irkutsk, mainly tarmac so was well 'scrubbed in'.
I have used Siracs off road. They performed well on dirt trails in southern Russia and the North Caucuses mountains. These were dry packed earth tracks or gravel/dirt routes. They were a good tyre on tarmac
Of the two, for pure off road, I would go for the Trelleborgs. But I would only consider them for greater than 80%+ off road use on the basis the other 20% was only relaxed 'transport and recovery' sections.
Not a tyre for town courier work!