Have a KLR650/Dauntless hack with a leading link with 18" front rim and a D606, 120-90-18. Works great, as I do mostly trails (with canine and camping gear in hack and wifey on pillion), but occasionally with freeway work to get to them. However, the tires howl on the slab, and I wanted to find a little more street oriented tire for those times when I have to ride a couple hours on the slab to get to the dirt. Found a 120-90-18 MEFO Explorer, with a pretty flat dual sport tread profile, thinking it would be ideal. Ordered it and it was delivered today. However, its a full 1.5" smaller in diameter than the D606! The D606 and the stock 21" KLR wheel tire were within 0.5" (that' s about 12.5mm for you Imperial units challenged folks) of each other. Other than the speed error, I'm concerned with potential handling problems, and to a lesser extent, ground clearance (the Dauntless sub-frame makes you lose almost 3"). As a minimum, I would prolly have to re-align the rig. So how can 2 same size tires be different sizes???
This can happen even if you buy tires from the same make. It's nothing but a fact. The tires don't have, they are made for the dimension that is written on them.
don't forget the D606 has all thos e really tall knobs. My KLR feels a full 1" taller when I have D606s on it compared to 50/50 dual sport tyres.
