Dunlop GeoMax MX31 front on a YZ450

[grayracer513]

I tried out one of the new Dunlop MX31 front today at a local track doing endurance laps. The surface was near sand/DG type high desert soil, packed hard here and there, but mostly either deep, coarse, DG sand or wet packed DG.

I thought the tire worked exceptionally well in the sand and the muddy areas, and that it worked surprisingly well on the harder parts. Haven't tried it in the desert yet, and won't be able to for a while because of the heat, but this may become my new favorite front tire.

[Aka.Goose]

Thanks for the report gray...

I'm still trying to decide whether to go for the 31s or the 51s...

I'd like to 31s at the track, but I think I'd eat em up quick during more varied surface, and hard pack trail rides...But I'd say most of my time is spent in intermediate terrain...Sooo??? 31 on front 51 on rear maybe???

[grayracer513]

I don't have the answer to that yet, of course, but based on how well the D755 held up, I'm optimistic. We'll see, I suppose. After yesterday, there is no significant wear on it yet.

Selecting tires for California, at least here at the bottom of the state, is a conundrum. There are lots of places here where you will encounter deep, soft silt, sand or coarse, loose DG, loose broken rock, and hard packed clay all in the same ride. Just about everything except real intermediate soil. It's a PITA, actually. Dunlop has been making an effort recently to build tires that have a more widely focused range of soil types in which they are effective. Some, like the 755, have been a pleasant surprise, while others like the 742FA have been a major dud, but they're trying.

Something to bear in mind is that when a tire is labeled "Soft", that is not a reference to the rubber itself, but to soft soil surfaces, the kind the tire was designed to work in. The rubber compound in the tread of soft soil tires is often fairly hard. Then there are tires like the 756, which is labeled intermediate, but wears rapidly if the wind blows over it while it's sitting there.

I picked the MX31 over the MX51 because I do a lot of desert riding, and sand, silt, and deep, loose DG are my biggest concerns. The M51 does look as if it would work pretty well in sand, but it's obviously made more for the intermediate/hard range.

Your choice.

[Aka.Goose]

Something to bear in mind is that when a tire is labeled "Soft", that is not a reference to the rubber itself, but to soft soil surfaces, the kind the tire was designed to work in. The rubber compound in the tread of soft soil tires is often fairly hard. Then there are tires like the 756, which is labeled intermediate, but wears rapidly if the wind blows over it while it's sitting there.

Well see, this changes my viewpoint a little...I was under the impression that soft terrain tires not only perform poorly on hardpack, but they also wore out rapidly, and were susceptible to having knobs split or knocked off by rocky terrain...

But if I'm wrong on that, and the durability of both are equal, then I'd go for the 31s...I do think a soft terrain tire works better on hardpack, than a hard terrain tire does in sand...

[Wiz636]

I have about five hours on an MX51 rear and it is my new favorite rear tire. It hooks up on pretty much everything so far both in straightline acceleration and cornering, especially cornering. I am impressed with the wear...nothing like the 756 which wears out almost immediately.

Gray, what is DG?

[grayracer513]

Well see, this changes my viewpoint a little...I was under the impression that soft terrain tires not only perform poorly on hardpack, but they also wore out rapidly, and were susceptible to having knobs split or knocked off by rocky terrain...

But if I'm wrong on that, and the durability of both are equal, then I'd go for the 31s...I do think a soft terrain tire works better on hardpack, than a hard terrain tire does in sand...

There's no hard and fast rule as to knob tearing, or any of that that relates to the soil type the tire is targeted to, really. It totally depends of the individual tire to a very large degree. Some of them tend to fall apart, and some hold up very well. Bear in mind, I'm talking front tires here. I'm not certain how a M31 rear would work for me, and I'm still pretty happy with the 952 in back.

In the simplest context, what makes a tire a hard or soft terrain tire is the configuration of the tread knobs. The amount of rubber area of the knobs themselves vs the space between them, sometimes called the land/sea ratio, is one factor. Soft dirt requires the knobs to penetrate the surface and reach down into the soil, so the knobs tend to be smaller in cross section. They also tend to be taller, and spaced farther apart so that there is more soil against each knob for it to push against.

Hard soils are more like pavement, and require the tire to "stick" to it. This means knob blocks with more surface area that are spaced more closely together. It also usually means shorter knobs, since the shorter blocks make the knob less prone to rolling over under thrust, which would cause a loss of tread contact. The knobs can only dig so deep in a hard surface anyway, so there's no loss in performance unless you run into a soft area.

The rubber near the tops of the knobs in hard terrain tires may be a lot softer than in a soft terrain tire because that helps with tread adhesion on hard surfaces.

[SXP]

Gray, what is DG?

Decomposed Granite.

[grayracer513]

I have about five hours on an MX51 rear and it is my new favorite rear tire. It hooks up on pretty much everything so far both in straightline acceleration and cornering, especially cornering. I am impressed with the wear...nothing like the 756 which wears out almost immediately.

Gray, what is DG?

Decomposed Granite.

'Zackly I's worse than sand. If it's loose, it's like a trench filled with ball bearings. If it's packed, it's like concrete with ball bearings on it. Then again, if it's wet, it's a lot of fun.

Interesting info regarding the MX51 rear. Have you tried a 952 in the back? How's the comparison?

[Wiz636]

Interesting info regarding the M51 rear. Have you tried a 952 in the back? How's the comparison?

I have run through a few 952's. I found them to be very versatile and useable on all types of terrain (as they were designed) and while they didn't do anything bad they also did not knock my socks off. As you know, they wear very well.

The MX51 however did knock my socks off in two areas in particular. The first was cornering where I could get on the gas hard and early out of corners. It hooked up so well in fact that I had to change my riding style a little bit, i.e., I was not getting nearly the outward drift when powering through corners so I was able to be more aggressive with the lean angle and throttle.

The second area that really impressed me was in low speed, tight trails. The tire would ride the side of ruts and come right up out of them if I wanted. Also, out of tight first gear hairpins and up a steep hill I felt like I was riding a tractor.

I have not ridden it yet in a high speed rocky desert-type terrain yet so I can't comment on chunking or flat resistance yet, although the carcass seems somewhat 'light' and I am a little concerned that it might not be tough enough to deal with high speed hits on sharp rocks. That said, I keep a Maxxis Desert IT in my garage for those rides.

[grayracer513]

The MX51 however did knock my socks off in two areas in particular.

Good stuff. What kind of soils have you ridden it in?

[clutchless]

I tried out one of the new Dunlop M31 front today at a local track doing endurance laps.

what track were you at?

[twenty34]

The MX51 however did knock my socks off in two areas in particular. The first was cornering where I could get on the gas hard and early out of corners. It hooked up so well in fact that I had to change my riding style a little bit, i.e., I was not getting nearly the outward drift when powering through corners so I was able to be more aggressive with the lean angle and throttle.

X2. The wear on the 51 is far superior to the 756 predecessor as well. I've been a big fan of the 404's, but I'm now leaning heavily to the 51's now. I've only run the rear thusfar, however - the 120.

[Aka.Goose]

Thanks for the info guys...I think I'm going to try 31s front and back, as I'm realizing I don't really ride hard pack during the hot and red banned summer months anyway...

[Wiz636]

Good stuff. What kind of soils have you ridden it in?

The first ride was an enduro in the western foothills of the cascades. Mostly wet single track with lots of mud, ruts and tree roots through a forest of conifers.

The second ride was a combination of tight, fresh single track and then long sections of two-track (kwad trails) that were fast but constant corners that were bermed up nicely but not rutted. Lots of quick direction changes with HARD braking and hard accelleration. Mostly dry packed dirt (not hardpack though) with few rocks.

[Aka.Goose]

Went to order the 31's today, but put it on hold til tomorrow...

Because, I couldn't decide on which width for the rear tire...

I'm told they don't have stock size (110/90x19) in the 31's...

The choice is either a 110/80x19 or a 120/80x19...

I assume the 110 narrower tire would be slightly better at tight handling???

[grayracer513]

Went to order the 31's today, but put it on hold til tomorrow...

Because, I couldn't decide on which width for the rear tire...

I'm told they don't have stock size (110/90x19) in the 31's...

The choice is either a 110/80x19 or a 120/80x19...

I assume the 110 narrower tire would be slightly better at tight handling???

Look at the recommended rim sizes. The 110/80 is made for the narrower 1.85 rim found on 125's and 250F's. The 120/80 is interchangeable with the 110/90 you're used to running.

[Aka.Goose]

Look at the recommended rim sizes. The 110/80 is made for the narrower 1.85 rim found on 125's and 250F's. The 120/80 is interchangeable with the 110/90 you're used to running.

DOH! Glad I waited...

[grayracer513]

He who hesitates sometimes makes better decisions.

[FinchFan194]

The first ride was an enduro in the western foothills of the cascades. Mostly wet single track with lots of mud, ruts and tree roots through a forest of conifers.

The second ride was a combination of tight, fresh single track and then long sections of two-track (kwad trails) that were fast but constant corners that were bermed up nicely but not rutted. Lots of quick direction changes with HARD braking and hard accelleration. Mostly dry packed dirt (not hardpack though) with few rocks.

I see you are from WA too. Was that second ride Tahuya State Forest?

[Aka.Goose]

He who hesitates sometimes makes better decisions.

LOL...Thanks yet again, Gray...

Although I generally live by the rule that hesitation hurts...