New England Mod & Meetup Thread: May 17 at Jared’s!!

Happy birthday @man17TRDoffroad

 

@man17TRDoffroad
Many more Manny

 

Posted this on MUD but doing so here for the sake of additional opinions
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Decision time: Probably going to test out the Toyo Open Country R/T Trail on the GX. But what size to go with? I'm driving myself mad (pun unintended) with the options.

Current tire that will be replaced:
BFG KO2 Load rtg. Dim. Wt.
34x10.5R17 (D) 3085 33.5x10.5 (32.5 mounted on the GX) 54

On the GX with the AR172 wheels, each corner is 79.31 lb/ea.

Here's the crux of my dilemma: I'm trying to figure out what the best combination of road manners off-road ground clearance, minimal MPG hit, and least likelihood of rubbing issues would be. Size options are:

Open Country R/T Trail Load rtg. Dim. Wt.
285/75/17 (E) 3970 33.9x11.3 63
255/80/17 (E) 3415 33.1x10.0 52

The 285/75 is appealing in the added ground clearance that comes with it being a true 34" tire, but it comes with the territory of a) possible rubbing on the frame and/or fender liners and/or pinch weld, and b) it adds 9# per corner. I have been desperately trying to stay away adding unsprung mass as we all know it stresses everything attached to it, which can be an easy point of failure when rock crawling like we do here in the Northeast. Unsprung mass can also severely hamper on-road drivability. Everywhere I go off-roading requires not insignificant highway time to get there-- usually in the 3-5 hour range. Maintaining road manners is a big priority. My concern in adding even more weight at each corner is worse acceleration and coasting, even further decreased MPG, and more strain on the rear door-mounted spare tire carrier, plus a higher likelihood of blowing an axle or tie rod in the woods.

That brings me to the 255/80/17, which is by the book a little smaller even than the KO2 that's on the GX now. However, this combo would weigh even less while adding the traction that the R/T Trail adds off-road over the A/T III (one of the other options at hand). I'm a big fan of the pizza cutter style (having run 255/85/16 on my first 4Runner and now the 34x10.5s now), just not sure the (slight) decrease in height will be noticeable or of concern. Regardless, right now this size is the front-runner; it seems like a happy middleground of aggressive tread but minimal impact on the truck's on-road performance.

Other options (as I posted about prior) are as follows:

Open Country A/T III Load rtg. Dim. Wt.
285/75/17 (C) 2835 33.9x11.3 59
35x11.5R17 (C) 2910 34.5x11.4 63
255/80/17 (E) 3195 33.1x10.0 51

Open Country R/T Pro Load rtg. Dim. Wt.
285/70/17 (E) 3750 32.8x11.4 60


Analysis paralysis is taking over.

Thoughts?

 

Looked at any of the few 255/85/17s? I think you should.

 

Yes... not an option at this time.

 

255/80/17

"Simplify and add lightness"

 

@CTSpruceMica and you think I over analyze things sometimes

Ross - are you still waffling on selling it?

There's a lot of math here, but the thing I want you to look at is the moment of inertia (the resistance to changing of movement, IE higher takes more gas to get going) uses the distance from the axis as an exponential (for both the wheel, and the spokes), and the mass as a linear relationship.

You add some pounds, and it won't do much.

Add an inch, and it's to the power of 2.


So if you're really focused on the MPG and driveability, my opinion would be the smaller diameter 6 ply tires that will be more squishy on the rough roads, and take less gallons per mile with the smaller moment of inertia. The trade off is they're not as cool, and you're driving a brick on wheels anyway, they won't be some magic wand that gets you to 50 mpg. You might go up by 1.

 

Lotus... Lexus..... close enough right

It's probably staying.

Man I wasn't expecting the math class haha. So it's not the mass that's the issue, it's how far away from the axle it is that causes the issue and is felt 2x? Either way, more mass = bad is the takeaway, whereas a tire that's 1" taller overall only nets 1/2" extra ground clearance

 

it's me, and I'm sober, you can expect math.

It is felt to the power of 2. This chart is a random google result, so ignore that it's time and growth instead of mass/diameter and inertia.



The distance is exponential, the mass is linear. Adding more mass does less than adding more size.

To be fair I would actually need to run numbers and see what the situation is.

 

Because I can



So in short, the KO2 and the 255/80 are roughly the same mass. 52 vs 54 LBm, but the radius is different. The resistance to moving (what takes gas to get going from a stop) is 10% more in the KO2 though.

 

I feel like I am in an ap geometry class right now

 

You're a wizard. In my decades of being obsessed with tires and everything related to them, I've never seen this concept explained this way. Extremely helpful!

 

Im a big fan of my 255 80 17 wildpeaks but still gunna step up to 35 x 10.5 kendas or 255 85 17 mickeys for better offroad performance, got a daily now so why not.

Both weight and tire diameter aren't as big of a deal when you are talking about " not insignificant highway time to get there" as it is for stop and go city type driving. I routinely get 18-20 in my truck(I go 67 on the highway) and my tire and wheel setup is 82 lbs I think. That is 100% highway with decent elevation involved.

Asthetics wise a chunky 255 80 17 is still a decent amount of tire and I think they look fine.

Do you happen to know what rear axle the 460's have? I know 470s have the V8 but still the 8.0 so those break a good amount.

 

Don't get me wrong, I'd absolutely love to go to a 35" tire, and am still considering it. But there's definitely more work involved in making it fit properly on the GX, which requires free time to troubleshoot, and I have very little to none of that these days.

460 has the 8.2" rear end

 

Meh, one mod day those would fit bump to strap lock to lock.

Looks like from the internet its the same. I thought I read somewhere that the washer fluid was an issue.

Does it require tubbing? Or letting it rub like @Brownmatthall

 

June 2023: Oh yeah that rubs, I need to fix that

June 2024: Oh yeah that rubs, I need to fix that

June 2025:

 

No tubbing but there's a pinch weld that needs to get reworked and the BMC that's done on mine might not be enough to clear, so that might need to be clearanced more for 35"s. And yeah washer fluid reservoir can be an issue but that's easy enough to relocate (relatively speaking).

Thing about a mod day is that I have no way of making it to one anytime soon

 

That BFG 34x10.5 is probably closer in dimensions to the toyo skinny 33 in reality, that's the move I'd make if I was trying to stay lateral with no extra work.

I get similar numbers on my truck with a wheel package coming in at ~85#. Now that it's warmed up I'm touching 300 mi/ tank again, it's great lol

I'm slowly just...removing all the parts the rub. Slowly but surely...