Originally Posted by Pleiades

Excel only do a 2.50x17/18, it's the widest they have before a big jump to the supermoto sizes of 3.50+ (which are all way too wide for the Tenere). The stock 2.75 is quite an odd size and isn't all that common from aftermarket suppliers.

A 140 will NOT fit on a 2.50" rim. Even a 130 is pushing it to the limit. The ideal size for a 2.50" is a 120/80, which is the 'normal' choice for off-road riders typically using this size of rim.