I am running a Perelli 140 on the rear of my s. I dont notice a loss in power but its been a while since I had my butt dyno calibrated. It does look better but I think the replacement will be a 130 to save $ and test it out.

 

The 140 on a supermoto is about like the 120 on the dual sport. I run a 130 on my 650 and wouldn't want wider. The key point to the smaller tire on the smaller bike is two fold. Lighter weight to spin with the less horsepower and easier to spin up if riding off road. The latter is when one is in soft loose terrain or mud and needs to spin the back wheel a bit to stay in the power band. If the tire is too big the traction is too great and the bike just bogs down.

We saw it all the time with newbies or know-nothings with their 125 "hill climbers", as that was what they frequently would be doing with them. They'd stick a fat honking 130 or 5.10 knobbie on them and think it made them better. The factory knew what they were doing when they put the 110 or 4.00 on them. First thing anyone who knew anything would do is put on a tire that made the bike quicker and easier to ride.

Just look at the back tire on a new 450 MX bike and you might be surprised to find they run a 120. The 250s probably still run a 110. Riding off road ain't about profiling. So if it is performance you want, stay 120. If it's about looks and profiling, do the 130.

 

My original question was not about performance, but if simply a 130 would work in the back. I have pointed out a few times that I got this bike to casually cruise some flat bayou trails. I am new to the dual sport bike scene, but not to bikes in general. Just enjoying the scenery with this one and I do want it to have a certain look and nice sound. Thanks to all who chimed in with suggestions and feedback on specific tires. (I attached a pic of me and my garage...I took some offense to being referred to as a "Know nothing", but do appreciate all the help in answering my specific question. It's either down to the Pirelli or the Dunlop 606.

 

My last rear tire was a Pirelli MT-21 130/90R18. It fit just fine and I liked it, but as TNC mentioned, it's tall so expect the bike to lean a bit more on its kickstand. I just switched the tire out to a 3.5 x 18" trials tire (approximately equivalent to a 90 R18 tire) and the power difference is noticeable, and I suppose the result of both less tire weight and smaller diameter.

 

I apologize for any confusion about the "know nothing" guys. Those are the same guys that stick a sock or a chunk of seat foam in the air box in place of the lost or destroyed air filter. They're also the guys who think everything should have bigger wider tires. Your questions clearly put you in the new rider area, searching for the answer. That isn't "know nothing", that's the sensible way.

One comment, the tire you are considering will probably be wider than the actual dimensional measure. Knobbies are usually significantly wider on the tread than a comparable size road type tire. Thus the smaller tire is the ticket. I can't measure to be sure, but I'm betting the 130 on the back of my KLX is as wide or wider than the 140 on the back of the 550.

 

Klx678: "I apologize for any confusion about the "know nothing" guys. Those are the same guys that stick a sock or a chunk of seat foam in the air box in place of the lost or destroyed air filter. They're also the guys who think everything should have bigger wider tires."
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As someone who has met my share of "know nothings" (and also as someone who has used a sock as an air filter myself!) I'd also add a few other defining characteristics of "know nothing" riders:

-they ride around with dry, dirty, loose, clattering chains
-they come to a stop by pulling in the clutch and coasting while giving the throttle an occasional blip
-they incessantly blip the throttle while stopped
-it takes them a full block after being stopped to get their feet back up on the pegs (or floor boards as the case may be)
-they wear flip-flops as footwear
-they use their passenger pegs as rear-sets
-they never use their rear brake
-they never use their front brake
-they have no front brake
-their chicken strips are wider than the squared-off centre of their rear tire
-their grips are higher than their armpits
-they think '2-stroke' means 'twin cylinder'
-they think 'freedom' can be achieved by making payments on a $50,000 bike
-they justify a loud pipe by believing it is saving their life every time they ride

I am all for the democratization of the sport, and I love seeing new people get into it, but every time I meet someone who claims to be a biker but is guilty of any of the above, I have a hard time taking them seriously.

 

Thanks for the clarification. I was definitely worried about rubbage from the knobbies. It seems there are quite a few people running 130's and even 140's on there S's, but sounds like 130's is a safe bet.

Thanks to all for the help.

 

130 is too big. I can get 120 Trakmasters cheaper, but use a 110 instead, as it's a better size. One of the guys I ride with has a 120 on his, and thinks it's too big.

 

Yeah bigger isn't always better, ask my wife....wait what? Did I just diss myself? LOL I always thought the 130 was just wider, is it taller too? A friend of mine who has the KLR 250 tried a 130 on his bike and it rubbed on the muffler, he went back to the 120.

 

The one I had was significantly taller. Parking the bike meant finding the "right" place. Unless it was pavement, I needed to find a sloped area or a rock or stick to put under the kickstand or the bike would topple.