Hi Folks. I asked Metzeler the same question. Here was their reply:
Hello
Please note one should always inflate tires to the correct tire pressure as
indicated in the owner's manual. However Metzeler North America has found the
air pressure suggestions listed in the brochure or on the web site will
improve mileage and customer satisfaction.
Check cold inflation pressure frequently. Correct tire pressure is crucial for
safe handling. Over inflation may impair ride comfort and reduce the contact
patch between the tire and the driving surface of the tires. Insufficient air
pressure will result in poor handling and cause a tendency for the motorcycle
to "wander".
In addition, improper and insufficient tire pressure will cause accelerated
tire wear, increased fuel consumption, less control and the possibilities for
tire failure due to an overloaded/under inflated operating situation."
Use this link to find out more about air pressures (mins and maxes)
suggestions based on load
http://www.us.metzelermoto.com/web/products/tire_pressures/default.pageTo see the tested and approved fitments please use this link to find the
fitment guide at the lower left side of the page
http://www.us.metzelermoto.com/web/default.pageTo find out the parameters of fitting tires with tubes please use either of
these links
http://www.us.metzelermoto.com/web/products/technology/maintenance/default.page
http://www.us.metzelermoto.com/web/products/technology/faq/default.pageIn closing Metzeler finds that running higher pressures (up to the max as
stated on the sidewall) will increase the life of the tire with no adverse
effects. Thanks for the question and have a great day.
NA Metzeler Consumer Affairs
877 202-4993
www.us.metzelermoto.comSo, after going to Metzeler's site, you end up 32F, 40R for the stock Speedmaster tires.
110/80 - 18 M/C 58H TL LASERTEC T Front - 32
PSI
170/80 B 15 M/C 77H TL ME 880 MARATHON - 40
PSI
Fitment Chart
TRIUMPH Speedmaster 900 (2003>2008)
HTH,
H.
