07

Project Tundra: 5000 Mile Evaluation of Nitto's New Ridge Grappler Tires!

by Mike Kojima

 

We were very pleased with the Nitto Terra Grappler tires that Project Tundra had been running for the last 7 years. We had over 60,000 miles of towing, supercharged burnouts, daily driving and off-roading on them including a day of driving hard around Willow Springs Raceway. We were very pleased to note that they still had at least 70% of their original tread and still worked quite well!

In fact, our tires were just starting to get a little cracked from age at the bottom of the tread blocks, and we were thinking that they would get hard before they were worn out. Amazingly, we were 100% confident that these tires would last well over 100,000 miles on the truck. Even though our tires still probably had a few more YEARS left on them, we got a call from Nitto and they wanted us to evaluate their brand new Ridge Grappler truck tire, and we gladly obliged them!

 

 

We used a Ridge Grappler in LT295/55-20 with a 10 ply E load range. We wanted the higher load rating because of our extensive tow use even though E load range tires are heavy, and the unsprung and rotating weight hurt ride comfort and performance. Well, Project Tundra is a work truck, and we will take the security that the higher load rating gives on those long tows!  

Looking at the Ridge Grappler, we were a little worried about on-road performance in dry handling on pavement and road noise, but Nitto assured us that we would not be disappointed in those areas, even though the Ridge Grappler had a look that to us seemed more off-road biased.

 

The Ridge Grappler has aggressive tread blocks with edge features that are pretty complicated.

The first point Nitto drove home with us is that the tire was designed first to be quiet, even though by looking at the tread, that is counter-intuitive. The tread has a variable pitch around the circumference of the tire to prevent harmonics from making the off-road tire humming noise that we find so irritating. The groove placement in the tread blocks was also designed to help cancel noise. 

The shoulder grooves were designed to help the tire to shed mud and to provide many biting edges, critical for off-road grip. The bottoms of the shoulder grooves have reinforcing buttresses to help keep the grooves open to help off-road grip and to reduce tread squirm during hard road driving. 

The grooves also have alternating tapered and stepped edges to give secondary biting surfaces just below the face of the block and the primary block edge. These really make a difference as the block edges get rounded with wear and on softer surfaces.  

 

In off-roading, the sidewall lugs make a huge difference in softer ground, as they are a whole additional area of dirt biting edges.

We usually don't go hardcore off-roading in Project Tundra, but we recently made a shooting trip where we had to repeatedly cross a sand filled wash and we found that the Ridge Grappler has surprisingly good grip in loose sand, even though they are not a sand optimized design. Other trucks that were with us struggled in the sand, and rocks and we didn't even need to get out of 2WD. 

The Ridge Grappler has two different sidewalls on either side of the tire; one looks more aggressive than the other. The side shown in these pictures happens to be the less aggressive side. We had asked the tire shop to leave the more aggressive side out to look badass but they messed up. The less aggressive side still looks pretty tough.

 

In this close up you can see the stepped and tapered block edges, and it is easier to see how they both aid dirt and mud evacuation and give additional biting edges. You can also picture how the sidewall lugs can really help dig through loose dirt. Note how new our tire looks even after 5000 road miles and an off-road trip!

 

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Comments
ginsu
ginsulink
Friday, September 08, 2017 2:39 PM
"Unfortunately, this was still at velocities way below the truck's potential cornering speed. "

Hopefully you are aware of the amount of fatalities due to truck rollovers.

This is just on tractor trailers, but the general information applies. This isn't so much for you Mike, but any potential readers.

Speed

Speed is the biggest contributor to rollover crashes, being involved in 45% of the crashes making up the LTCCS sample. This greatly exceeds the 23% of all large truck crashes attributed to “Traveling Too Fast for Conditions” (FMCSA 2006).
Speed-Related Rollovers

Two aspects of the conditions under which the crashes occur help explain the role of speed. First, rollovers occur when the front wheels are turning the truck more quickly than the cargo it is carrying; the faster the speed of the vehicle, the greater the difference. Second, large trucks operate chiefly on Interstates and other high speed roadways. As with speed related incidents in general, it is not the very high speeds associated with “reckless” driving but rather speed that exceeds what is safe for the particular combination of vehicle and road characteristics. As noted earlier, many crashes have multiple causes, as is evident in the fact that the number of specific causes adds up to 149 where speed related crashes total only 108.

Curves

It is in handling curves, mostly on- and off-ramps, that excess speed becomes the biggest factor, accounting for 77 rollovers, two-thirds of all those that are speed-related. Semi-trailers appear the most vulnerable to curves in that straight trucks, which make up a third of the trucks involved in rollovers, have only 10% of those occurring on curves. This largely reflects the relatively lower roll stability of the trailer. Because the reasons drivers exceeded safe speeds on curves differ substantially, they are further sub-categorized.

Misjudgment

The single biggest cause is simply misjudging the speed at which the curve can be safely entered. Over four-fifths of the crashes occurring on curves are attributable to misjudgment. The judgment problem is aggravated in many locations by posted speed limits that are too high for loaded tractor-trailers. One proposed solution is to post lower limits for semis at such locations.
Crousti
Croustilink
Saturday, September 09, 2017 3:54 AM
Crashes usually happen because of poor judgment, that is stating the obvious. That includes things like "that brake disc still has some life in it" and various "i will fix that oil leak later".

Limiting roll also limits rollover tendency, which is what mike did.
Mike Kojima
Mike Kojimalink
Saturday, September 09, 2017 10:18 AM
Of course trucks roll over, there are warning labels every 10 inches inside
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