The "compensate" meant gearing slightly lower to make up for a taller tire. I made up a spreadsheet a few years back to compare gearing and tire diameters when I was looking at 17s for my 650. I wanted to be able to swap out wheels with minimal differences so I didnt' have to alter sprocket sizes.

As was said, bigger means heavier. Heavier will take more power to rotate and to deal with higher friction from bigger contact patch. Heavier will also affect suspension as it is unsprung weight, but few of us would really notice that. One other thing is larger diameter may hit inner fenders, but only when significantly bigger. A 120/80 versus a 120/90 would likely not be an issue.

Bigger diameter or wider width will slow turn in. On street bikes I found 10% increase or reduction in profile made a difference, especially on the front wheel, but still does on the rear too. I also found that one tire size up or down significantly affects handling. Wider tread slows turn in, in a brief simple description you are levering against the width when you turn, leaning in. I found going from a 100/90 to a 110/90 on the front of a street bike made it handle like a truck, steering was really slow. So when I wanted quicker handling I dropped one tire width on one bike I had and I dropped one profile size on the front on another bike.

That is why I really do some serious thought when changing tire sizes. It's not just fatter or skinnier looking, it's how it will work. Wider/bigger diameter = slower handling. Narrower/smaller diameter = quicker handling. I like a quick handling street bike at least on par with my dual sport.

I also look at what is used off road as well. Back in the two stroke days, the 125s ran about 4" wide tires, my CR250R only ran a 4.5" tire. Now the 250 enduro and MX bikes run a 110 knobby which has a width of around 4.8" which is the width of a dual sport 120. Seems the off road metric sizing is a bit strange as noted on Dunlop's site, the knobby 110 is more like a 120 dual sport size and the knobby 120 is more like the 130 dual sport size. That is for an enduro which has at least 50% more power than the 250 dual sports and for the MX which nearly doubles the 250 dual sport hp. Even the 450s only run a 120 which is 5.2" wide.

So there is good logic staying at OEM size or, in my case, going smaller seems to suit what need be done for off roading in woods riding. Desert riding in a lot of sand may or may not be the same, wider tires may "float" better on the sand and protect rims from rocks in desert riding. A bit of thought never hurts when deciding what tire sizing to run on a bike.

 

I'm really really loving the tires I put on recently:
Kenda K760 Trakmaster II for Rear
Kenda K772 Parker Desert Tire for Front

I'm able to lean pretty far in the street and still get great traction in mud/dirt/grass.

 

How big is the 772? with the word Desert in the name, makes me think it's a bit bigger than the normal 21. Not a comment on choice, just a question on the tire size since the name includes Desert and they used to run wider tires back when. I know there are reasons for oversize if it is. But... I am curious.

I'm a bit of a tire geek when it comes to sizes and all. Kind of like wanting to try an 80/100 versus the normal 90/90.

 

Not wide at all. Skinny tire. It's called Desert because it's 6-ply, so really tough/stiff carcass that can withstand rocks and cactus, and ***** don't chunk off (harder compound as well).

I actually got the skinniest sizes possible for my tires for both my front and rear.

Here's a page with pics

 

Man! 6 ply! I remember how hard it was to put on a 4.00-18 six ply and how hard it is to do a 3.00-21, I can imagine putting that 6 ply 21 on.

That is one wild tread. Really sparse. I guess I'm not used to seeing that sort of tread having been in the east here over all the years.

Thanks for the link.

 

Yeah, I picked these tires for my first ever tire change! I also put heavy duty inner tubes in them! It did take me hours to get both tires changed. I'll probably be a lot quicker in the future, though.

Yeah, it's a desert tire but I don't actually ride in any sand or rocks (I'm a good 6 hours away from that kind of terrain). I just wanted a good off-road tire that was puncture and cut resistant so I don't have to worry about flats as much. It seems like it's a good all-rounder for offroad work and would do well for east coast terrain as that is similar to the type of terrain I'm riding on.

I wasn't sure if the sparse treads would be an issue or not. So far I've never slid out or lost much traction on pavement/dirt/grass/mud. Front tire tracks really well. No vibration on road, either, but I do use Ride On tire sealant which may help balance and the highest I get to is around 50 mph.

It's been raining so much here in north central Texas, I've actually done mostly mud riding since the tires were put on

I try to lose traction and slide around corners, but now that I'm no longer on my 50/50 IRC GP1 tire, it's a lot more difficult! I have to either be going much faster, or go through much thicker mud in order to slide the back tire.

 

[QUOTE=klx678;520742]Key question is for performance or looks?

I like the looks of the Mefo Super Explorers. But can only find them in two sizes of 18's.

would a 150/70-18 or 140/70-18 fit?

KLR650.com - MEFO Sport Tires



Mefo - Aviciouscycle.ca

 

WAY too big! IMHO
they might fit but would suck all the power.

 

[QUOTE=KLX25O;520853]So, what do you like about them? The name or the tread design...



A bit of difference in tread, not a big name, but not much and that tire can be had to fit in four or five sizes from 4"-5" in 18" size at very competitive pricing.

 

[QUOTE=klx678;520864]

I do like the tread design. I have decided either the Mefo Tire or Duro Tire. But if a bigger tire would give poor MPG. I'll have to rethink and get something else.