Torrential rains and widespread flooding have resulted in few riding opportunities, so it's a good time to play in the shop and mount the Mitas E-07 tires that arrived recently. Here're the rear and front E-07 tires next to the MT21 on my front wheel.
I'd been looking for a 50/50 tire that offered more durability than the knobbies (MT-21 front, D606 rear) I'd left on the bike since last season, in the hopes of doing a long ADV ride somewhere this summer. The Mitas E-07 has gotten great reviews for durability, and apparently it edges out the Heidenau Scout K60 for grip and handling. However, I couldn't find many reviews of these tire on smaller DS bikes so I'm curious to see how they work on my WR250R.
The first thing I noticed when my shipment arrived was how heavy the box was. There was a set of tubes in the box as well, but really--it was kinda shocking. When you're on a small ADV bike with little horsepower to start with, it's important to watch weight--especially on wheels, where the extra rotating mass really affects suspension performance, acceleration, and handling. So I was concerned about how the E-07 would feel in action and weighed my last three tire combos for comparison.
Here's the line-up for comparison, with Scouts on the left and E-07's on the right, with my D707 in the middle.
All tires have approximately the same dimensions for carcass and tread on front/rear. Weights are approximate: the Scouts and knobbies were worn, and my fish scale was giving me trouble.
Heidenau K60 Scout
4.00-18: 6.0 kg
Pirelli MT21, 90/90-21: 3.8kg
Dunlop D606, 120/90-18: 5.5kg
Mitas E-07 (50/50 dirt/road)
90/90-21 Dakar: 4.4kg
Wow, the rear E-07s is more than 3kg (6 lbs) heavier than the D606! Must be all that depleted uranium Mitas adds to their rubber to resist wear.
Oh, these were going to be hard to mount. Just getting the inner tube into the rear tire before mounting it on the wheel was a challenge. In fact, the E-07s were the hardest tires I've ever mounted, made worse by cold temperatures. There hasn't been any hot sun to pre-heat the rubber in over a week, and leaning the tires over a baseboard heater barely helped. A couple of hours had slipped away unnoticed while I cursed and used every trick I knew to pry these solid blocks of rubber onto the wheels I'd built up last fall. Eventually the tires yielded! However, if I flat in the boonies, I would be tempted to just push my bike into a swamp and go buy a new one rather than try to change the tube. On the other hand, the rubber may be stiff enough to ride for quite a distance without any air. Hopefully I don't need to test that theory.
As part of the exercise I swapped out my 48T sprocket for a 45T (leaving the 13T up front), on the theory this would give me just enough extra top-end for the highway while not being as sluggish as the stock 13/43 gearing on trails and with baggage. This required shortening my chain by two links because the axle was already at the back of its travel.
Time for a rip around the country block over a mix of mud, gravel, and pavement, and in the pouring rain.
I immediately noticed the lack of acceleration: a combination of tire weight and the higher gearing. To my surprise, and despite having the throttle pinned, I just wasn't accelerating beyond 95km/hr (GPSed) on a straight flat section with no wind. This is one reason why Yamaha and Honda really need to offer a 400-450cc version of their small ADV bikes--the extra ponies make all the difference when carrying baggage. When I shifted into 6th it felt like a useless gear, more of an overdrive.
Otherwise, handling felt pretty good: no discernible wandering in the ruts, solid traction in the puddles and rain. However, the tires did feel harsh because of the stiff sidewalls (the Dakar version incorporates and extra sidewall ply to make it stiffer), and running about 20psi front/25psi rear. Airing down about 5 psi and warm tires will certainly help.
Nevertheless, coming from a 48T rear sprocket, the torque of the 45T sprocket just felt too low. So I swapped it for the 47T I'd run last year. Haven't re-tested it yet, but I suspect it'll be a reasonable compromise. Now that my chain is 2 links shorter, I was just able to put it together with the axle all the way forward. That left about 1cm between the rubber and the mud guard on the swingarm. It's a new chain, so after it breaks in a bit the clearance should only improve as I move the rear axle back.
The jury's out on these tires until I get a chance to ride them in more summer-like conditions (i.e. above 10C and on dry pavement and trails). If not for the wear rating I'd probably not choose these tires for my bike. At these weights they're clearly not aimed at small bikes, and I wouldn't hesitate to run them on a big ADV machine. Obviously I'm pushing the WRR (and these tires) beyond their intended usage so there's going to be some compromises. And if the weather doesn't improve this year I may need to revert to knobbies anyway, regardless of the wear implications!