CW Tire Review: Dunlop Geomax MX32 & MX52

Dunlop tires are currently the most popular way of grabbing traction in AMA motocross and supercross, but there's a big disparity between what the top pros use and what the public can purchase. Now, though, the engineers at Dunlop are changing that by creating an all-new line of tires that can be sold in a dealership on Friday and then actually raced in Anaheim Stadium on Saturday. Cycle World had a chance to test these new MX32/MX52 Geomax tires at a recent Dunlop press introduction, where we learned that this new rubber is a worthy successor to the proven Geomax line.

Previously, Dunlop’s Geomax line consisted of three main patterns: The MX31 (for sand and mud), the MX51 (an all-around/intermediate tire) and the MX71 (for hard-packed, blue-grooved conditions). The new Geomax line replaces those three tires with just two different patterns, the MX32 and MX52. Both tires feature common technology, but there are a few differences that set them each apart.

Designed for soft-to-intermediate terrain, the MX32 rear tire features increased bending within each block. By eliminating the internal tie-bars, Dunlop has increased contact feel and performance in muddy conditions. Additionally, fewer blocks are now needed in the center row because the multiple block distribution essentially varies the pitch and angle of each center block. On the front tire, the mid-shoulder knobs are staggered and are sized differently for better grip and more response, while a chiseled shoulder block (technology used previously saw on the MX31 tire) was designed for better grip at a lean.

Dunlop’s team of pro tire fitters spooned on fresh rubber for the press. These guys change tires easier than most people change lanes while driving!

On more hard-packed tracks, the MX52’s staggered center block distribution is aimed at helping the tire absorb impacts, such as whoops and square-edged bumps. The front tire also has a unique knob design that means the tire works in just one direction for optimum traction.

That stated, the main benefit of both new Geomax tires stems from the concept of “a block within a block” knob, which is essentially a patented process that layers a small, stepped block on top of an existing knob in such a way that each knobby features progressive control in terrain types. Broc Glover, Dunlop’s Senior Manager of Motorcycle Racing, Off-Road, explains this Progressive Cornering Block Technology (PCBT): “This Progressive Cornering Block Technology (PCBT) came about from load tests that show how a tire puts pressure on the ground. We started noticing that the external portions of a knob had all the pressure, while the internal portions of the knob actually had a void of pressure. By actually elevating the inside of the knob, we were able to develop an aggressive tire that is good for starts and good for straight-line performance, but also works very well when the track gets harder and the bike is leaned over in slippery conditions.” Essentially, Glover is stating that placing a small knobby on top of an existing one has brought about a whole new level of performance from this rubber.

“The MX32 front tire was first brought out for the Daytona Supercross of last year,” Glover explained. “Ryan Villopoto, Ryan Dungey and Marvin Musquin all put it on, and the next thing you know Villopoto has not raced a pro race without that tire. At Anaheim 1 this year, the entire 450 podium was nothing but MX32 tires, front and rear. We’ve never had this kind of consensus among racers, who are usually quite picky and don’t always agree on tire choice. Now, with this new group of tires, it’s much easier for us to supply the pros because they all agree on what to run. It’s really been a blessing for us.”

A closer look at the MX32 rear shows the new PCBT (Progressive Cornering Block Technology).

On the day of Dunlop's intro, the Milestone MX test track featured a medium to high traction level with packed clay and loamy berms. Dirt Rider brought out a variety of 125cc two-stroke, 250 four-stroke and 450 four-stroke machines, allowing us to try the MX32 and MX52 in several sizes. Here, we noticed that the MX32 front tire improved front-end feel and traction over the previous MX31 and MX51 versions in all conditions. The new tire actually makes the steering feel "heavy" because the tire is at maximum grip under initial lean. The MX32 can be leaned over more to each side with less pushing than the older Geomax. Although we did feel some under-steering in ruts as the front tire would grab and want to pull the front end down more than the MX52, the MX32 is still a better choice, even in hard-packed conditions or slippery mud.

The MX32 rear offers great forward bite in intermediate/soft-terrain ruts and corners. Lean traction has also been improved over the MX31 and MX51. The "block within a block" side knob design seems to work well under every lean angle we tried at Milestone. Our only complaint: When the track surface was hard pack, we could feel the carcass of the tire roll when accelerating from flat corners, when really pushing down on the rear end.

As for the hard-packed tires, the MX52 front gave us improved lean angle, as the tire will actually bite when there is nothing to bank off of on slippery/hard flat corners. It can lean well in softer loam but will push a little on the exits of corners. The MX52 rear was impressive. When the track dries out, this tire does have better forward traction than the MX71 or MX51. Traction at lean angles is improved over the MX71, and the tire will give you grip when you need it in hard-pack conditions. Our testers could actually feel the tire digging in and creating forward momentum without getting excess wheel spin. However, unless conditions are really hard everywhere, we still would prefer the MX32.