Hello fellow klxers. Sorry if this has been covered. Has anyone tried a 140 on there klx. I know it will reduce some power. I bought another bike to duelsport and from the factory has a 140 that is too aggressive for riding on the road for my liking. Thinking it will be tamer on the klx and I can get the use out of it. It is a dot Michelin enduro competition 140/80/18.

Oh and don't worry my KLX is going nowhere! Just has more company.

Thank you

 

Why don't you just measure it?
I had an oversize Sedona (120/90-18 I think) on my 350, it barely fit, I had to cut the chain guard back to clear the ****. I went back to the standard size (Sedona 110/100-18) after that.

 

We've had this discussion before about larger tires, and I seem to recall that a 130 was about as big as was reasonable to install for decent fitment. That said, I think anything bigger than a 120 is a detriment to the handling, power delivery, and off road performance. Even on my highly modded 300 jugged equipped KLX-S with a pumper carb and full exhaust, I only use a 110...and I even have 14/50 gearing. A huge rear tire on this bike creates a stickbug effect to the handling aside from what the added weight and diameter does to performance. A brand new Yamaha WR450F uses a 120/90-18. The WR250F competition model uses a 110/100-18. What does that tell you?

 

Yamahas are wuss bikes and just can't take it?

 

Somebody had to say it!

 

Thanks guys. I haven't taken a tape to it just eyed it up and it looks really close. The swing arm is wider on the other bike for sure. I knew it was a long shot. Will most likely just leave it and be extra careful till replacement time.

Thanks again

 

FWIW, I am running a 4.00 dual sport Duro Median on my stock bore 250. I went narrow to maximize power to the ground instead of turning over a heavy tire, plus where I ride the narrower tire is a benefit knifing down to terra firma when you hit the mud or really loose stuff. It also won't bog as easily when doing so.

I learned that back when riding/racing a two stroke 125... resist the urge to put on a fat tire for more traction, it wouldn't work as well due to the low power of the 125 versus a 250 or 500 - and even the 250 worked better with no more than a 4.50 and usually a 4.00.

Besides with the smaller tire the KLX actually looks more motocross-ish.

 

Larger tires sap power so bad...it's astounding how much. I've been doing some experimentation with tire size, and so far have run an 80 front, and a 130 rear (seperate times). I can say that running smaller tires definitely improves handling and power. That huge rear tire saps so much power, and makes that awful stickbug effect in real technical stuff.


Basically, tire size doesn't matter much for traction. What matters is PSI, since this is what alters the contact patch. A 120 tire at 10psi will have the same amount of contact with a surface as a 130 at 10psi. All that extra surface area is wasted.

In fact, larger tires have reduced traction on most surfaces since they have to deform less to make the same contact patch. Deformation for tires is kinda like a hand going and grabbing at something, all those individual ***** close to grip at the gravel or whatnot.


The only benefit of larger tires is that they take longer to wear, and in the (for most of us) rare circumstance you are in terrain that is so soft you sink (mud, snow) far enough for your side ***** to get a bit of grip.

The disadvantage is power sapping, the rear wheel overtaking the front in terms of steering, and more likely highsides.

The benefit of smaller tires is more control, more power, better traction on intermediate terrain. Also better gas mileage, but marginally.

Disadvantages are, your rims are likely to get dented or scratched, they have a much shorter lifespan (they have to deform more and thus get a bit warmer, along with shorter tread). And you might have some trouble if you take a lot of luggage or a passenger around with you.

 

I am on board with everything you said except a few points, minor points.

The wider tire gets pinched up when mounted on a narrower rim, possibly putting less tire on the ground on pavement. We experienced that in the 70s when putting 5.10 tires on bikes like the Kawasaki Z1. They had stupid narrow tires, as was the case back then, a 4.00-18. Putting a 5.10 on the stock rim looked good but it turned out they wore faster, they were pinched in at the bead pinching in the entire profile and ending up with little, if any, added tread on the ground over the 4.00. A wider rim was needed to work with the wider tire.

That translates in to what you commented about - pinched up tire, doesn't deform enough to put more tread on the ground. Fact is a slightly narrower tire will spread out more on the rim possibly putting a bit more tread on the ground. I don't encounter much rocky stuff, so I am not too worried about the lower profile. It would be different if I was. I'd to a stock 120 if so.

The fatter tires do give more flotation if that is needed, like desert and other similar surfaces plus digging in a bit better in dense snow. They also give better rock protection in hard pack rocky terrain. There are fatter profiles for the front knobbies, going a bit over the standard size front for those conditions, 3.25-21 was the one I remember, over the standard off road 3.00-21. I'm running a 90/90 because that is what Duro has and I have had good experience with them over the past 15 years. On the 250 it might be nice to get an 80/100 if they made it.

When it comes to off road, it takes some consideration of what will work based on observation. Off road racers in softer tight terrain go smaller profiles, desert/rocky terrain riders go a bit bigger. You seldom see any of those who had racing experience running any of the really big stuff - unless they're on a Yamaha TW/BW or a Honda Fat Cat