Yamaha WR250R and WR250X Forum

Hi Dayne.  Good tyre choice!  The MT43 takes me everywhere.  I was surprised that the tyre is rated as tubeless, but a quick nip out to the garage confirmed it!

I've always used heavy duty tubes in my MT43s without problems.  On a spoked wheel, you don't really have another option.

I've been told that they are bastards to fit when new (very tight on the rim and hard to seat).. I've always "cheated" and paid my local bike shop to fit them, although he has told me in the past that he has had to put up to 70psi in to get the tube to seat on the rim properly!

Don't really have any suggestions as to where to buy them, as my local shop, In Chains, Ringwood supply and fit for me.  I'm a bit of a believer in "use it or loose it".  That includes your local bike shop.

Glad I could help.

Worth mentioning;  the MT 43 is the best trials tyre for trail bikes.  It has excellent road manners and good off road grip.  Don't be tempted to buy other brands of trials tyre.  While they may have more grip/softer compound off road, they are a pig on the tarmac and wear out very quickly.

Ahhh - I think 6lbs hardly inflates an HD tube Steve. Have you found small beads of rubber when you have changed tyres and rub marks on the tube? If so, those are the tell-tale signs.

I found this message on the TTR forum:

Our local guys have been having trouble with the valves ripping out as the UHD tubes were moving back and forth inside the tyre on each acceleration or deceleration.

A member just bought a new UHD tube for the front of his bike and he did some tests before fitting.

UHD tube; 9psi,  tyre not quite filled;  10psi, just filled; 11psi completely filled but not "gripping" the tyre.

Standard Cheng tube; 3psi, filled; 4psi, completely filled and bulging.

The other thing was, inflated outside the tyre, the UHD tube starts bulging unevenly at 9 to 10 psi and the standard tube seemed to inflate more evenly but you can't go beyond about 4psi.

Conclusion, you should run a minimum of around 15psi on a UHD tube as it requires more pressure to fill the tube and stop them moving, a lot more pressure.

More here

These things always get more complicated the more they get talked about!  In some cases I think ignorance really is bliss!

And just to complicate things more, I have HD tubes on the WR, whereas I had UHD tubes on the DR.  Those UHD ones sure are thick.  I think they could run on the road without a tyre at all!  I am using about 12psi for normal trailriding on the WR.  I will have a good look if (when) I take the tyre off for any reason.

Good topic.