Help choosing new tires

[Chrisazm]

I have been running MT Baja Boss AT for a while on my 392. They are heavier which slightly changes acceleration and braking. Fuel economy is about the same. Larger diameter cancels out increased weight. Great grip and the treads don’t throw rocks from gravel roads. I hope that helps!

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[Blues Fan 30]

I have been running MT Baja Boss AT for a while on my 392. They are heavier which slightly changes acceleration and braking. Fuel economy is about the same. Larger diameter cancels out increased weight. Great grip and the treads don’t throw rocks from gravel roads. I hope that helps!

It does yes thanks! The weight was my biggest concern on them but seems most people dont view it as a real issue.

 

[Ratbert]

Larger diameter cancels out increased weight.

Huh? I'm pretty sure you meant a larger diameter exasperates the negative aspects of increased weight, not cancels it out.

 

[roaniecowpony]

It does yes thanks! The weight was my biggest concern on them but seems most people dont view it as a real issue.

It's not. The real story on the Mickey Thompson BB AT tires is that they are tough as hell, including the sidewalls. If you put street performance ahead of off-road performance, something like the Falken AT or BFG AT is probably more suited. But for off-road toughness and traction, this is probably the best AT and it has the siping to be a good rain tire too. It's certainly a long shot better all around when you include off and on road than K02s.

 

[Chrisazm]

Huh? I'm pretty sure you meant a larger diameter exasperates the negative aspects of increased weight, not cancels it out.

Not what I meant at all… but thanks!

 

[jadmt]

It's not. The real story on the Mickey Thompson BB AT tires is that they are tough as hell, including the sidewalls. If you put street performance ahead of off-road performance, something like the Falken AT or BFG AT is probably more suited. But for off-road toughness and traction, this is probably the best AT and it has the siping to be a good rain tire too. It's certainly a long shot better all around when you include off and on road than K02s.

crazy enough they are the only tire that I have ever punctured a sidewall on.....and that goes way back to the 70's....freak luck I know....disregard the bald spot on my head

 

[roaniecowpony]

crazy enough they are the only tire that I have ever punctured a sidewall on.....and that goes way back to the 70's....freak luck I know....disregard the bald spot on my head

There's always an example proving absolutes are not....

But, I wish I had a picture of the 3 SUVs we rented on a goat hunt in NM, 2 of them up on stacked rocks and all the tires off of them in the third SUV, which had a mix of wheels on it. All K02s. All flats from tiny cactus and brush and rocks.

 

[grimmjeeper]

Not what I meant at all… but thanks!

First off, diameter affects the vehicle easily 10x more than weight.

Larger diameter makes the tire harder to turn.

More weight has a very small impact on acceleration. Once you ignore the anecdotes and get into real world comparison under controlled conditions, you find out that the effects of weight are down near the rounding errors.

Hope that helps.

 

[c20040215]

I have wanted to try Nitto Trail Grapplers since they came out. In 2023 we bought a Gladiator Mojave that the dealership had put a Mopar lift and 285/75R17 Trail Grapplers on. At 23,000 miles I just replaced them. My set of Trail Grappler tires were the shit, and not in a good way. Here is what they looked like at 23,000 miles. Alignment was verified and was correct. They were rebalanced and ran smooth with no bounce.

These tires were much louder on road than others we have recently used (Toyo MT, Cooper STT Pro), and they wore out a lot faster. I read a lot of reviews on Nitto's website because it seemed like my experience with these tires was not the norm. It turns out that about 4 reviews were positive and then one horrible review, and so on, over hundreds of reviews. When ordering new tires I talked to one of the managers at the local Les Schwab dealer I buy tires from. He is very much into off-roading, as are many of the other employees there. He has a Toyota Land Cruiser with 38s, and even the super cute female receptionist has a 2-door JK with a Metalcloak long arm suspension with 37s. The manager had noticed the same inconsistencies with Nitto tires, so he started keeping track of the plant they were manufactured in. Apparently, there are two plants in the USA and one plant in Mexico that make Nitto tires for North America. He noted the bad tires came from the Mexico plant, which is where mine were made. I have absolutely no way of verifying this, it is just what he told me.

I've always had good luck with Toyo MT tires, and just six months ago put a set of 40s on my JLUR. But for our Gladiator Mojave that needed new tires I went with Toyo Open Country RT Trail tires. Check them out, they got my vote.

Tell me more about the super cute female receptionist who has a 2D Jk with a metalcloak long arm with 37s.

Sorry you have bad experience with Nitto.
Mine 37" RGs have had over 40,000 miles and still have around 13/32 left (I do 5 tire rotation). This past weekend I mounted them on some beadlock wheels and they are still smooth without any balance weights.

This is my second set of Nitto RG. First was 285/75R17. I have been please with them and my next set will be 38x12.50.. Only complaint is that the cost of gaining one extra inch is way too high.

Toyo owns Nitto and they share manufacturing facilities in North America.

 

[Blues Fan 30]

Well I landed on the BBATs and ordered them from Discount Tire last night to be installed August 9th. They were able to actually find me a price match even better than I could find which saved a little bit of money on top of the current $100 rebate on Mickey Thompson tires. I am going to be starting the axle swap on the 8th so I will have all tires pulled which will make it nice and easy.

 

[Chrisazm]

First off, diameter affects the vehicle easily 10x more than weight.

Larger diameter makes the tire harder to turn.

More weight has a very small impact on acceleration. Once you ignore the anecdotes and get into real world comparison under controlled conditions, you find out that the effects of weight are down near the rounding errors.

Hope that helps.

So the diameter of the tire itself doesn’t tell the entire story. The difficulty or ease in increasing or decreasing rotation rate is determined by moment of inertia, which is a complex formula involving radius and mass. The radius squared so the radius is a larger factor but if you are increasing by only 1 inch that is a small percent of the tire size so then it depends how much weight you are adding to the tire. If you are buying the same type of tire but a larger diameter it is likely the increase in diameter will be more of a factor than increase in weight.
On the other hand if you have a lighter tire and a larger radius it is possible to have a wheel and tire that is the same or easier to turn depending how light the tire is by comparison. Also have to consider the mass of the wheel. This is why some people buy lighter wheels when buying heavier tires to try to mitigate the effect of the heavier and/or larger tire.
For a 10x increase in moment of inertia based only on tire diameter you would need to more than triple the diameter of the tire.

So in going from 34.5 inch KO2 to 36.75 MT BB AT, I bought a tire with more mass and also a larger diameter so both of those factors make the wheel significantly harder to increase or decrease rate of rotation. I added about 6% radius but 25% heavier tire so the weight was more of a factor than the increase in size. Both of these combined increased the moment of inertia by about 30% so yes I do notice a difference.
To take that a step further axles contribute to the moment of inertia calculation also but since those stayed the same I am just ignoring that part.

My original point was only about MPG. Since it takes more fuel to accelerate but the tire diameter is larger so slightly fewer RPM on the engine at any given speed, less fuel is required to maintain speed. For my driving style these two cancel out and I have the same MPG with my 37s that I did with my 35s. That’s what I was trying to say with fewer words. Have a good one!

 

[grimmjeeper]

So the diameter of the tire itself doesn’t tell the entire story. The difficulty or ease in increasing or decreasing rotation rate is determined by moment of inertia, which is a complex formula involving radius and mass. The radius squared so the radius is a larger factor but if you are increasing by only 1 inch that is a small percent of the tire size so then it depends how much weight you are adding to the tire. If you are buying the same type of tire but a larger diameter it is likely the increase in diameter will be more of a factor than increase in weight.
On the other hand if you have a lighter tire and a larger radius it is possible to have a wheel and tire that is the same or easier to turn depending how light the tire is by comparison. Also have to consider the mass of the wheel. This is why some people buy lighter wheels when buying heavier tires to try to mitigate the effect of the heavier and/or larger tire.
For a 10x increase in moment of inertia based only on tire diameter you would need to more than triple the diameter of the tire.

So in going from 34.5 inch KO2 to 36.75 MT BB AT, I bought a tire with more mass and also a larger diameter so both of those factors make the wheel significantly harder to increase or decrease rate of rotation. I added about 6% radius but 25% heavier tire so the weight was more of a factor than the increase in size. Both of these combined increased the moment of inertia by about 30% so yes I do notice a difference.
To take that a step further axles contribute to the moment of inertia calculation also but since those stayed the same I am just ignoring that part.

My original point was only about MPG. Since it takes more fuel to accelerate but the tire diameter is larger so slightly fewer RPM on the engine at any given speed, less fuel is required to maintain speed. For my driving style these two cancel out and I have the same MPG with my 37s that I did with my 35s. That’s what I was trying to say with fewer words. Have a good one!

You are completely ignoring the fact that you're not just changing the rotational velocity of the tire. The tire is on the ground and is being driven to change the linear velocity of the vehicle.

That's where the diameter of the tire really factors in. The diameter of the tire directly impacts the force applied for vehicle acceleration. It's why you change axle gears to match tire diameter changes. The transmission can compensate a little if you're close. And modern transmissions are better than ever. But they can only help so much.

Tire weight is just minor parasitic drag which is why it's such a small factor in actual vehicle performance.

 

[jadmt]

I constantly switch back and forth between two sets of tires with nearly same measured not advertised diameters but one set weighs 20lbs a tire/wheel more. No noticeable difference in mpg but if i were drag racing for pink slips i would put the lighter set on for the race.

 

[grimmjeeper]

I constantly switch back and forth between two sets of tires with nearly same measured not advertised diameters but one set weighs 20lbs a tire/wheel more. No noticeable difference in mpg but if i were drag racing for pink slips i would put the lighter set on for the race.

For me it would depend. How's the traction between the two? A heavier tire with far better traction would be my choice, assuming the lighter tire doesn't hook up well. Any tire that doesn't hook up is bad for drag racing.

But yeah, if they both hold traction enough to not break loose, the lighter tire gets the nod.

Thing about weight and MPG is that it will impact around town driving with stop and go. But on the highway, you're not accelerating much and the effect of weight drops to nearly nil.

 

[c20040215]

You are completely ignoring the fact that you're not just changing the rotational velocity of the tire. The tire is on the ground and is being driven to change the linear velocity of the vehicle.

That's where the diameter of the tire really factors in. The diameter of the tire directly impacts the force applied for vehicle acceleration. It's why you change axle gears to match tire diameter changes. The transmission can compensate a little if you're close. And modern transmissions are better than ever. But they can only help so much.

Tire weight is just minor parasitic drag which is why it's such a small factor in actual vehicle performance.

I am not a physicist but here is my experience.
When I went from 34 to 37, the size went up by around 9% and the weight went up by around 17.6%. The felt difference is significant.

When I swapped out the wheels recently, the tire size is unchanged but added about 16% of the weight from the beadlocks. I could feel the extra weight when I mount them but I cant say I feel any difference in performance, or see any noticeable drop in fuel economy.

For sure 16% added rotational mass has some impact but its not nearly as significant as diameter.

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