I bought my XT recently and it came with new tryes.
I would have preferred the Bridgestone or Dunlops but they fitted Kingstires.

I would like to know the correct rear tyre pressure for on road use (I know I would need to let a few pounds out for off road).

The owners manual says 21 PSI up to 90KG and 32 PSI over 90KG.
I weigh 90KG fully kitted out.
The shop I bought it from says 26 PSI rear.

Try it out =)

I cant feel if im running 1,5bar or 2,2bar

Its usually somewhere in between.

I have tried it out at 26psi and 21psi.
For some reason I feel more confident leaning/cornering at 21psi in the rear.

But I just wondered if there was any science behind having tyres at certain pressures for road use.
I guess more of the tyre is in contact with the road at lower pressures.

You don't say what tread pattern (road, adventure ot knobbly) ?

Just set them to what YOU prefer!

Many riding Dual sport bikes on the road run too high a pressure, holding onto some preconceived but misguided theory left over from 500 lb. sports bikes. IIRC, your XT weighs "about" 365 lbs. wet. (166 kgs.)

Yamaha are wise to post a variance based on load/rider weight. But tire types can vary some too and of course conditions.

I think you are very close to spot on. I would run:
26 psi rear
22 psi front.

I think you will find you will get the best wear with these pressures for most dual sport 50/50 tires. Many will tell you to run 32 rear, 28 front, or even higher. I have done it and it may ride OK but tires will wear faster. A lower pressure is also much safer in any sort of wet condition and also in aggressive cornering. Trust me on this one.

If you were to load up the bike or add pillion, I'd go to maybe 30 rear, 25 front, more / less.

Thanks for the replies.

The guy at the shop told me they are biased towards road use.

Rear tyre is 4.60 17 62S whatever that means.
Front is 90/90 -21 60T.

Mickey you are correct, the bike with oil and petrol is 365lb ish.

I'll try out 26PSI in the rear.

I thought the Yams were 18" rear wheels - and older DR's 17" ?????

Mine's 21 front and 17 rear. 1994 XT600E.

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2006 XT660R daily ride, 1994 XT600E about to be reborn, Blog: http://goingfastgettingnowhere.blogspot.com/

Most of the xt600's are 17"

from 1990 and up, and i believe the early models were 17 too, then it changed to 18, and then back, as i recall it.

blackdog, what on road tyre pressures do you use?

21F and 26R. I check them fairly regularly, but a few lb either way doesn't seem to make a lot of difference. (The Pan should be 42/42, and even 2psi out makes a huge difference to the handling.)

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2006 XT660R daily ride, 1994 XT600E about to be reborn, Blog: http://goingfastgettingnowhere.blogspot.com/

From what I recall on the tyre session at Ripley (UK HU meeting 2009), advice on tyre pressure in manuals is a good guide on where to start. However change the make/model/profile/size/weight carried etc then the advised pressures will not offer optimum wear or grip.

Take the guide pressure when cold, start riding, when the tyres are warm (20 mins?) check the pressure. If the pressure has risen 10-15% then you are about right. If the pressure has risen less than 10% let a little air out. If the pressure has risen more than 15% then add some air.

For example:
Cold 20 PSI
If pressure is optimum when Warm pressure should be 22-23 PSI
If it reads 21 PSI then take let air out back down to 20 PSI and repeat before your next ride with tyres from Cold.
If it reads 24 PSI then add air to 25 PSI and repeat before your next ride with tyres from Cold.

Make a note of your optimum roads pressures when solo, loaded, with pillion etc.

Take note I am not a qualified tyre guru but this is what I practice. It has certainly helped me with improved handling and extended tyre life.

That sounds like a good approach, thanks.

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2006 XT660R daily ride, 1994 XT600E about to be reborn, Blog: http://goingfastgettingnowhere.blogspot.com/

The problem with the above technique is moisture. If your air source contains a lot of moisture (very common) then this can affect readings/results rather sharply giving inaccurate readings.

This is why at the race track they use Nitrogen in tires. Very stable. Depending on where you get air, moisture content can vary. At Petrol stations this is especially true. If adding/subtracting air is done at home with a bicycle pump then should be very little moisture affect.

The other confusing factor is how altitude effects tire pressures. In the UK where you have little altitude variance, not such a problem. In North and South America altitudes can rise and fall 7000 ft. (2200 mtrs.) in just ten or 15 miles. Higher altitudes, higher pressures. From sea level up to about 8000 ft. equals "roughly" 10% rise.

Riding hard also affects pressures. High speeds and lots of time on the side of the tire heats the air, thus raising pressures.

When touring I try to check pressures twice a day. Once in the morning, along with chain care, oil level check and basic safety walk around.

At the end of the riding day .... while everything is still warm (usually done at a petrol station) ... I check tire pressures, fill tank, clean and lube chain and check oil level. This has worked pretty well in the last 200,000 miles or so. Before that, I was pretty clueless about maintenance and had lots more breakdowns! Modern tires are such a joy compared to the bad old days when everything wore out so quickly. We are very lucky to be riding today!

Front - 24 PSI
Rear - 28 PSI

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Triumph Bonneville 800 (2004), Yamaha XT600E (1999), Honda XBR500 (1986).