MT's vs AT's, 17's, 18's vs 20's discussion

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Augster

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A little demonstration of the tire "flexing" over the rocks and bumps to give an idea that there is sufficient sidewall squish to soak up some of of the trail harshness... Not the best example, but this little hill allowed the group to dismount and film each other; normally through some of the really rough stuff, including crawling some significant rocks and zipping over washboards no one is out filming us.


Suffice to say, ridin' F-Rated 20's wasn't an issue!
 
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Christian92

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Alright, I was about to post a new thread regarding my previous roast session by established members by me posting my 38x13.50r20's set up and that I had finally realized something super important, but I'll just piggy back on your thread here.

What matters here a ton is force needed to turn each wheel individually. Watch me bust out my bill nye here:

Common knowledge is that force = mass times acceleration. This means your truck works more depending on how much heavier the truck is obviously right? Except when you break it down into 4 corners it goes like this: minimal force required to turn a wheel is torque divided by wheel size. So yeah, no wonder all the Raptors run 17's dude. It's easier to get the truck moving because physics. I have 20's with E tires and let me tell you the truck is HEAVY to start rolling and stop. @Nex said he went back to 17's and now I understand exactly why. Hence why I've been looking for 38's for my 17's now.
 

Augster

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What matters here a ton is force needed to turn each wheel individually. Watch me bust out my bill nye here:

Common knowledge is that force = mass times acceleration. This means your truck works more depending on how much heavier the truck is obviously right? Except when you break it down into 4 corners it goes like this: minimal force required to turn a wheel is torque divided by wheel size. So yeah, no wonder all the Raptors run 17's dude. It's easier to get the truck moving because physics. I have 20's with E tires and let me tell you the truck is HEAVY to start rolling and stop. @Nex said he went back to 17's and now I understand exactly why. Hence why I've been looking for 38's for my 17's now.

Weight of the unsprung wheels definitely has a play!

But weight is also based upon brand of rim and tire selected: a steel bead-lock rim will weigh more than milled non-beadlock aluminum rim, and how "solid" the rim is (e.g. fewer spokes, large gaps versus mostly solid with small round holes) will affect overall weight.

For my wheels, here's the weight breakdown between Trail Grappler 35x20 on Fuel Maverick 20's, versus Trail Grappler 35x17 on Fuel Maverick 17's:

Trail Grappler 35x12.5x20 = 76.83 lbs + Fuel Maverick 20x9 = 37 lbs = 113.83 total pounds

On my scale, it showed 111.2 lbs, but has an accuracy of probably 3%, which tracks with 113.83 pounds listed by the manufacturers

img_6824_d83e9e43b0bb874ad3402837deb2d302667ffc9b.jpg


For the same tires and rims in 17", Trail Grapplers 35x12.5x17 = 79.89 lbs + Fuel Maverick 17x9 = 30 lbs = 109.89 total pounds

The net difference for my chosen brand of tires and rims is only 3.94 pounds per wheel. This would not be significant enough for me to feel any appreciable performance difference.

But then add several hundred pounds in heavy duty aftermarket bumpers, trail jack, tools, air compressor, recovery gear, electric cooler, camp chairs and table, food and snacks, extra water and fuel, trail happy doggy and one fat man and his SO, the truck is loaded down for bear. You certainly notice the weight difference! All this "extra" stuff is what really hits the pants.

To compensate, I have both a 5-Star performance tune and Pedal Commander, which wakes up the 6.2 enormously! Depending upon what setting I have on the Pedal Commander, I can easily smoke the tires with my setup.

If that's not enough, I have Whipple in the cards for the future, and when the time comes, punching and stroking out the block to 6.6... :p

Now, I'm just comparing Apples-to-Apples in regards to 35" diameter. Switching to 37's, which it seems you and I both are on course to upgrade to such, we need to examine the net "effective torque ratio" to the pavement: going to a larger diameter wheel will reduce the overall ratio to the deck, in addition to adding more unsprung weight (Ridge Grapplers 37x12.5x20 = 81.06 lbs each) to the mix. The result is our trucks may feel more sluggish off the line. Some have resorted to regearing to bring the net ratio back within the usable power band of the powertrain. As I have forced induction in the works, which adds gobs of low-end torque, I should have no need for regearing (I've already had 37's on it, albeit stock rims and mild AT tires, and my current tune/Pedal Commander setup easily handled it).
 
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FishFreak

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Weight of the unsprung wheels definitely has a play!

But weight is also based upon brand of rim and tire selected: a steel bead-lock rim will weigh more than milled non-beadlock aluminum rim, and how "solid" the rim is (e.g. fewer spokes, large gaps versus mostly solid with small round holes) will affect overall weight.

For my wheels, here's the weight breakdown between Trail Grappler 35x20 on Fuel Maverick 20's, versus Trail Grappler 35x17 on Fuel Maverick 17's:

Trail Grappler 35x12.5x20 = 76.83 lbs + Fuel Maverick 20x9 = 37 lbs = 113.83 total pounds

On my scale, it showed 111.2 lbs, but has an accuracy of probably 3%, which tracks with 113.83 pounds listed by the manufacturers.

For the same tires and rims in 17", Trail Grapplers 35x12.5x17 = 79.89 lbs + Fuel Maverick 17x9 = 30 lbs = 109.89 total pounds

The net difference for my chosen brand of tires and rims is only 3.94 pounds per wheel. This would not be significant enough for me to feel any appreciable performance difference.

But then add several hundred pounds in heavy duty aftermarket bumpers, trail jack, tools, air compressor, recovery gear, electric cooler, camp chairs and table, food and snacks, extra water and fuel, trail happy doggy and one fat man and his SO, the truck is loaded down for bear. You certainly notice the weight difference! All this "extra" stuff is what really hits the pants.

To compensate, I have both a 5-Star performance tune and Pedal Commander, which wakes up the 6.2 enormously! Depending upon what setting I have on the Pedal Commander, I can easily smoke the tires with my setup.

If that's not enough, I have Whipple in the cards for the future, and when the time comes, punching and stroking out the block to 6.6... :p

Now, I'm just comparing Apples-to-Apples in regards to 35" diameter. Switching to 37's, which it seems you and I both are on course to upgrade to such, we need to examine the net "effective torque ratio" to the pavement: going to a larger diameter wheel will reduce the overall ratio to the deck, in addition to adding more unsprung weight (Ridge Grapplers 37x12.5x20 = 81.06 lbs each) to the mix. The result is our trucks may feel more sluggish off the line. Some have resorted to regearing to bring the net ratio back within the usable power band of the powertrain. As I have forced induction in the works, which adds gobs of low-end torque, I should have no need for regearing (I've already had 37's on it, albeit stock rims and mild AT tires, and my current tune/Pedal Commander setup easily handled it).

Such important considerations Augster, and you're spot on that heavy unsprung weight is very 'seat-of-the-pants' noticeable! That's why I'll be stickin' with 35" tires. With all your O/L gear, what front/rear spring and suspension setup are you runnin'?

I run my Screw unloaded mostly, with stock beadlocks and BFA A/T's, and a 5 Star 91 octane performance tune, and absolutely LOVE the snappy response! This tune changed the throttle mapping and the trans shift logic, so much so that I can't see the need for a Pedal Commander? I'm already spinnin' the tires if I leave a traffic stop with anything more than ultra-light right foot ;) !
 

Augster

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Such important considerations Augster, and you're spot on that heavy unsprung weight is very 'seat-of-the-pants' noticeable! That's why I'll be stickin' with 35" tires. With all your O/L gear, what front/rear spring and suspension setup are you runnin'?

OEM suspension.The rears are too bouncy for me with all that gear. My intent is to put 'er under the knife and install King 3.0 Gen 2 Coilovers and Rear Bypass shocks. This will require new front housing buckets and rear shock mounts to take advantage of the full travel of the Gen 2 suspension, along with Deavers.

I have King 2.5's on my regular F150 and those improve the off-road capabiilities tremendously, but still don't fully touch an OEM Raptor.

I run my Screw unloaded mostly, with stock beadlocks and BFA A/T's, and a 5 Star 91 octane performance tune, and absolutely LOVE the snappy response! This tune changed the throttle mapping and the trans shift logic, so much so that I can't see the need for a Pedal Commander? I'm already spinnin' the tires if I leave a traffic stop with anything more than ultra-light right foot ;) !

I did a lot of testing, and for most of my driving style, the PC18 does more seat-of-the-pants improvements over the 5-star performance tune. Now, I have the 89-octane tune as the gas here in Cali is already uber expensive and as this is my daily presently, my monthly fuel bill exceeds $1k/monthy running 89. No way do I want to dump more gas money on a daily by switching to 91.

Once I hit the Whipple, the Rap will be relegated to mostly off-road duties so the tune will be for 91+.
 
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FishFreak

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I did a lot of testing, and for most of my driving style, the PC18 does more seat-of-the-pants improvements over the 5-star performance tune. Now, I have the 89-octane tune as the gas here in Cali is already uber expensive and as this is my daily presently, my monthly fuel bill exceeds $1k/monthy running 89. No way do I want to dump more gas money on a daily by switching to 91.

Once I hit the Whipple, the Rap will be relegated to mostly off-road duties so the tune will be for 91+.
Hey Augster, I was looking at the Ford specs for our 6.2 L engines, and it showed that our engines develop 11 more HP running 91 octane, vs 89. Granted, this CA winter alcohol blend may cut into that benefit, I figured 11 hp for 40 cents more per gallon is the cheapest 11 hp I'll ever find this side of runnin' full E85, which gives terrible mileage, right?

My 5 Star 91 Octane Performance Tune works fantastic, and makes my truck squeal those 35/12.50R17 KO3's off the line every time if I'm not very careful with my right foot. I'm gonna pickup the lightest set of 20" wheels I can find, and try out my 35/12.50R20 Toyo MT's. Why not? I need tires, and the hit I'd take selling my nearly new MT's is not too far off the price of a set of wheels. If they drag down my Screw's launches :(, I'll sell em and put some new tread on my factory beadlocks.

Now to find light weight 20's!

Thanks for all the info in your PM to me, re-reading it and replying now....
 

Christian92

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Hey Augster, I was looking at the Ford specs for our 6.2 L engines, and it showed that our engines develop 11 more HP running 91 octane, vs 89. Granted, this CA winter alcohol blend may cut into that benefit, I figured 11 hp for 40 cents more per gallon is the cheapest 11 hp I'll ever find this side of runnin' full E85, which gives terrible mileage, right?

My 5 Star 91 Octane Performance Tune works fantastic, and makes my truck squeal those 35/12.50R17 KO3's off the line every time if I'm not very careful with my right foot. I'm gonna pickup the lightest set of 20" wheels I can find, and try out my 35/12.50R20 Toyo MT's. Why not? I need tires, and the hit I'd take selling my nearly new MT's is not too far off the price of a set of wheels. If they drag down my Screw's launches :(, I'll sell em and put some new tread on my factory beadlocks.

Now to find light weight 20's!

Thanks for all the info in your PM to me, re-reading it and replying now....

Hey Augster, I was looking at the Ford specs for our 6.2 L engines, and it showed that our engines develop 11 more HP running 91 octane, vs 89. Granted, this CA winter alcohol blend may cut into that benefit, I figured 11 hp for 40 cents more per gallon is the cheapest 11 hp I'll ever find this side of runnin' full E85, which gives terrible mileage, right?

My 5 Star 91 Octane Performance Tune works fantastic, and makes my truck squeal those 35/12.50R17 KO3's off the line every time if I'm not very careful with my right foot. I'm gonna pickup the lightest set of 20" wheels I can find, and try out my 35/12.50R20 Toyo MT's. Why not? I need tires, and the hit I'd take selling my nearly new MT's is not too far off the price of a set of wheels. If they drag down my Screw's launches :(, I'll sell em and put some new tread on my factory beadlocks.

Now to find light weight 20's!

Thanks for all the info in your PM to me, re-reading it and replying now....
I'll save you some time on looking. I've been looking high and low for lightest 20's and have found that Methods 316 win at about 34 lbs, which is a tad lighter than stock beadlock 17's which weigh 36.6 if I remember correctly.
 
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FishFreak

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I'll save you some time on looking. I've been looking high and low for lightest 20's and have found that Methods 316 win at about 34 lbs, which is a tad lighter than stock beadlock 17's which weigh 36.6 if I remember correctly.
Thank you Christian! Went on their site and the 17x8.5 wheel is a feather light 26 lbs! Oddly, I didn't see a 20"? 18" was the largest listed. Yea I think stock beadlocks are about 35-36 with the trim rings and hardware.
 
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FishFreak

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Lets talk about offset for a sec: lets presume we're using a 9 inch wide wheel, 35" tire. What are the main reasons Raptor guys seem to like their wheels tucked in so tight? Clearance for 37" tires so they don't hit the fenders? Less stress on bearings and ball joints? Steering?

I heard to run the RPG UCA's with the massive 1.5" upper ball joint, you need a wheel with less than 5" backspace? I might get those. To get that 5" BS you need a 13mm offset, and that pushes the outer wheel lip out just a hair over 1" What's the big deal about that? FWIW, I don't mind 1" of poke cuz I'd like to get extended Bushwhacker Pocket Flares for the added protection and the blacker color and hardware look. Don't like my grey stock flares with a tux black screw.
 

Christian92

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Thank you Christian! Went on their site and the 17x8.5 wheel is a feather light 26 lbs! Oddly, I didn't see a 20"? 18" was the largest listed. Yea I think stock beadlocks are about 35-36 with the trim rings and hardware.
Yeah I believe the 20's are only available specifically in the "gloss black" color.
Lets talk about offset for a sec: lets presume we're using a 9 inch wide wheel, 35" tire. What are the main reasons Raptor guys seem to like their wheels tucked in so tight? Clearance for 37" tires so they don't hit the fenders? Less stress on bearings and ball joints? Steering?

I heard to run the RPG UCA's with the massive 1.5" upper ball joint, you need a wheel with less than 5" backspace? I might get those. To get that 5" BS you need a 13mm offset, and that pushes the outer wheel lip out just a hair over 1" What's the big deal about that? FWIW, I don't mind 1" of poke cuz I'd like to get extended Bushwhacker Pocket Flares for the added protection and the blacker color and hardware look. Don't like my grey stock flares with a tux black screw.

The dude's on here with more experience probably can get into the nitty gritty of it, but from what I've read on here it all boils down to the wheel being able to be tucked/stuffed inside the fenders when jumping the trucks. Which becomes harder to do the more negative the offset becomes other than what came from factory.
 
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