Alright let's get really, really into it.
So I went from the
OE 21x?"+54 ET wheels on Yoko G056 P275/50r21 XLs 113V
to my
17x8.5" +25 ET Methods on P285/70r17 Toyo OC A/T III 117T
And before i can best answer your question i recommend you read all that I've written on my now admittedly bad fitment choice and the outlined area below.
I even made a stance thread that no one really contributed to with actual stance photos not mountain glory shots if you want to see how these things poke.
In that regard, Ive shared a lot of my experiences and experimentation with the forum to some rather limited feedback so I hope this is a good chance to hash out what is actually on my mind for the sake of this awesome community. Im gonna apologize in advance for the wall of text that is coming.
Please note that nothing in my opinion is directed at the Toyo AT3 which is an amazing tire that I highly recommend.
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My objective was to fit the smallest possible wheel, with the largest diameter tire without any rubbing or modifications and get the best ride comfort and fuel economy i could. In doing this I wanted to 1) reduce weight if at all possible. 2) Add as much sidewall as possible.
While I was able to achieve BOTH of those requirements i fell short of my objectives because my understanding was flawed.
The issue is more about the science of wheel / tire fitment and what goes into that choice.
Coming into this i knew practically nothing except how to read tire sizes and have gotten into some back and forth on the forum about how to actually go about doing this THE RIGHT WAY. Part of that is the fundamental principle of what the PSI is to be run on any non OE setup.
There is a lot of WRONG information that is often purported as fact and sometimes (in my case in particular) completely dangerous. There is one particular member who firmly and stubbornly subscribes to a false understanding of the guidelines to appropriate inflation. There is a lot to read on that and many arguments to sift through but suffice to say i fell into that trap myself.
Ive blocked
@gaijin so for any other MUD members reading this, please do yourself a massive favor and don't take ANYTHING he recommends as fact. Hes absolutely flat out wrong and even as a complete novice, after a year of research, i have confirmed ALL of my suspicions were true. Heres how i know....
Due to my ongoing struggle of meeting my needs for a comfortable and SAFE ride, I got the chance to escalate my questions to a very very kind and knowledge professional who actually made the tire i own. I spoke to the head tire design product engineer at Toyo. He was kind enough to take an hour of his day to help me figure out why i wasn't satisfied with my setup and how we could rectify it. He was also one of the product managers at Toyota who designed and launched the 200 series, is a huge advocate of AHC (he is the reason the 100 LC received it as an option) and he helped me figure out why my AHC was leaning after a year of pulling my hair out about it. (Thats now solved it and I am going to do a write up on that as i know a lot of the LXs lean to the drivers and probably yours too)
I am super grateful for that opportunity and Toyo/Nitto is an awesome company and I will never buy another tire brand unless i have to.
Basically I was never able to get a comfortable ride out of my tire at any PSI that did not cause instability, poor milage, and tons of sidewall flex.
Here is my new understanding of the situation that I hope will help you make the right choice for you and why i do not recommend any high aspect tire in P rated for our trucks.
First, you CANNOT run a like for like load range tire anything below the door jamb PSI. In our case for any P rated tire, no matter what its load rating is, it must be at least 33 PSI. Going from a 113 to a 117 load rating does not mean you can run it at a lower PSI because it can support the minimum load required for the vehicle weight. I made the mistake thinking that such a large aspect tire at such a low PSI would be an equivalent but much more comfortable change. Boy was that wrong.
According to industry standard calculations which you can do here:
RCTIP Calc (just match the load rating if your OE size isn't listed)
My 117T P285/70 can SUPPORT the weight without structurally compromising the tire at 26 PSI which I believe is actually the minimum allowable for the P / size.
At that pressure it rides like a dream on a cloud. The issues however become very apparent when you are actually driving and trying not to die.
When you run such a low pressure you are: creating too large a contact patch and much more friction, removing too much sidewall rigidity, adding too much flex and steering wobble, and creating A-LOT of unnecessary rolling resistance. These things are due strictly to the geometry and forces at work. Thats it. They have nothing to do with the tire or the vehicle. Its just a function of how much downward force is applied to the wheel, the lateral forces to the sidewall, the amount inner surface area the air is occupying, the contact patch that creates, and the heating and cooling of the tire as it tries to absorb all that.
I noticed from playing with it so much that it did not drive well at anything below about 32-34 PSI. I actually almost crashed doing some experimenting during a turn.
Now any actually competent tire recommendation will tell you the same thing, which is why i was so confused when Discount Tires store computer database suggested my pressure to be set to 32 PSI.0 To put it very simply, just because the tire can roll and not explode or de-bead at 26 PSI does not mean you can simply expect a 6,500 lb vehicle to handle on that. When OEMs choose tires and their respective pressure, they are trying to achieve a balance of the all of the above and more (things like rebound rate which plays into suspension damping and a whole lot stuff we can discuss later). When you try to get a large tire and run it low, you throw all that away.
Dont fall victim to the idea that you can just create comfort by dropping PSI like I did.
To understand this better let talk about comfort. Tire comfort itself is due to a multitude of reasons but mainly to two things; the construction, and the pressure.
These two things are inextricably linked and simple enough. The more robust carcass can handle more internal pressure (although absorbs more heat and thus these why LT tires all have lower speed ratings)
As far as construction goes, we know that there are equivalent ply ratings, compounds, tread geometry and so on. These things are pretty much as they seem. Its when we get into pressure that it gets more interesting... As you can see above, i thought a lot of what was obvious to me was straight forward to understand and linear in logic. That is not the case. The thing that helped me the most was understanding that pressure alone is not enough to judge how soft the ride will become.
Let's take the example above and dissect it a bit. I have an OE 275/50r21 at 33PSI, it has a 5.4" sidewall due to the aspect. Now take a 285/70r17 at that same pressure with a 8" sidewall. Which one would have "softer" ride? The 8" sidewall you say??? Shouldn't they both offer the same softness as there is the same pressure of air holding up the car? No. Actually you are right to think the 285/70 would be softer. The question you have to answer then is why? Why with the same forces of air is one softer than the other? What i was explained and have since read more on really helped me understand and make my choice of a new C load AT3 very easy.
(BTW as soon as these are installed next week I will add more to this thread).
Pressure alone does not dictate anything but instead its the pressure relative to VOLUME. While I don't have the formulas or know the details, this is apparently part of how the load ratings are calculated in the first place. When a plus size P anything tire is given a higher load rating, its not because of any additional pressure capacity. As a matter of fact my old yoko 113s could get up to 50 PSI while my current 117s can only recieve up to 44. This also confused me before.
We all know the it's the PRESSURE holding the vehicles weight but there is more to it than just that when it comes to comfort.
When a particular tire is inflated to a particular pressure of air, that indicates of how much air has been squeezed into it. We also know that air is compressible.
When you try to compress a filled tire, you are working against that total pressure and construction pliability but its really the volume / quantity of AIR inside that has the capability of compressing as well as the overall size of the tire itself that can stretch accordingly. The more actual air is in there, the more empty space between the molecules that can be compressed. Comfort is much better accommodated when there is a larger volume of air and tire to create it.
It's easy not to see that, but likewise its very clear now that i have my head wrapped around it.
So, long story short, I do not recommend running a P rated tire if you are looking for comfort. You will have to fill that to a HIGHER pressure than you think in order to preserve everything other than comfort and will be way too close to the max PSI when at operating temp. For example, our manual states to fill rears to 39 PSI when towing. That would be an absolute joke to do on a tire with a max PSI of 44 for the towing stability. I would rather recommend you fill your tires to a lower percentage of max than that. I will be going from my Ps @ 77%-82% fill (32-36 PSI/ 44 MAX) to a more comfortable C @ 72%-80% (36-40 PSI/ 50 MAX).
I never thought that a C tire would be the right choice for comfort for me but when you apply the principles of tire engineering CORRECTLY you will see that you really cant cheat the system like I thought I would be able to do. As a matter of fact, if you use the calculator or do it by a hand per the Toyo RCTIP
Guide I can run a C load at a safe minimum (equivalent of OEM) of 38 PSI safely and due to the inherent stiffness in the LT variant will probably achieve a more stable ride even at that. Even better than that calculating the OEM towing recommendation of 39 PSI gives a safe minimum of 40. This is giving a useable and safe running PSI range of 12. On the Ps i would have only have a safe range of 10 and a usable range of 8 when starting at 36 PSI (where i know the tire is handling best). Also when off-road, your LT metric will also be much less likely to de-bead due the additional sidewall materials and bulk. Im a mall crawler so i cant comment exactly, but Ps aren't gonna roll off the wheel and people do run them but LT is going to be safer for that nonetheless. Lots of other stuff about punctures you can dig up too but thats another topic.
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Now in your case heres what i would suggest.
Don't try to reinvent the wheel and definitely ditch the 20s. There is just too much bump steer, they are too heavy for what they are and ride like trash and will do you no good off-road. They also don't do the AHC any justice, but if it weren't for AHC Lexus would be shipping 18s.
Speaking of, dont get 17s. Get 18s.
With the bigger brakes of the '16+ years there is NO room to clean anything at all. I can barely squeeze in my smallest wheel woolie.
In addition 17s don't look right on the LX and i regret that from a style perspective. I think 18s look perfect.
I only went 17s because i found the only non Rock Warrior wheel in a proper offset that weighed the same.
People will differ here, but I don't like spacers. I would rather just get the right wheel and Rock Warriors are not my cup of tea anyway with the locker ring and rivets.
I shaved 10lbs a corner and honestly still suffer a loss to MPG due to going 285 wide, the tire lift, and the pressure situation being more resistive.
I highly suspect when i add that 9lb for the C load back that with less flex of the tire, my efficiency will be practically unaffected as i can keep the tire more "round".
THE BEST offset for the platform, again IMHO, is +35. If you look at my stance thread i poke ever so slightly enough to make a mess of my body panels. Unless you get PPF applied or large mudflaps i would go less wide. +35 would tuck perfectly and an 18x9 wheel would fill the well just right. I would look in the tire and wheel database to see if that will rub being .5" wider and .4" closer to the hub. Definitely don't get the ones you linked. That is not going to fit larger tires at +60 ET unless you want spacers. But also what do they weigh? Its VERY difficult to find weight specs on any wheels. Part of the reason i went method is its all listed.
In regards to wheel width let me say this very clearly and I hope i can get others to comment.
An 8.5" wheel IMO is not enough width for a 285 tire. A general rule of thumb is you want to achieve as square a tire/wheel profile as you can while maintaining a good bead angle and pressure. As it is now my tires have to curve back into the wheel more than 3" in order to fit into the 8.5" wide bead. Toyo suggests a 7.5-9.5 " wide wheel for my size tire in their specs but I would bet that they er on the side of caution for bead friction.
Next time around i will lean more to the larger number than the middle and thats 9". If you want photos id be happy to show you what I mean.
In regards to wheel weight, I have found that going lighter is not always the answer in a TUNED suspension like ours. I firmly believe that you should stick as close to the OEM fitment weight as you can on your LX and definitely try your best not to overly exceed it. At the acceleration that a wheel typically engages with the shock, 10 lbs has a lot of impact on the forces transmitted. When i dropped weight on my setup i constantly experienced the damping to be more muted as the shock was fighting a lot less and felt like the truck was over-sprung. I have learned that In an actively damped tuned suspension like AHC, the fluid and gas pressures are receiving a lot less force than they were tuned for at our different settings. Comfort feels a lot more like normal did in damping (not harshness of ride). I now know better than to try and cheat that system as well and im getting back to my OEM 80LB per corner. As it is now I would never want to live in comfort mode as there is too much brake dive. I need the weight to plant the vehicle and actuate the shocks the way Lexus intended. If we had more control over AHC i would not be saying this. Sometimes i wish i didn't have it for build out flexibility but it is just so damn good and practical.
Now onto tires. I CANNOT RECOMMEND TOYO ENOUGH. Not only do they make excellent tires but i assure you they care about this community and consider all that it is we care about too. The OC AT III was partly designed by a land cruiser lover and is quickly becoming a forum favorite.
I would say the only negative i have with them is they are a bit noisier than i thought they would be and the sidewall is not the most aggressive. I dont have the most experience on AT or Hybrid or Mud tires but there are many here that do. What i do know about is the huge experience i had above and this vehicle in particular which we share ownership in. I have made several posts about how good my tires were specially in the TX freeze where i live in a very hilly area. I was blown away by snow and ice performance climbing hills like it was nothing while cars were piled up at the bottom including a g-wagen. Im not sure about sand performance but I know the tread pattern is damn well thought out in all the right areas.
@bloc has a lot of experience with his and generally off road tires so he can comment on his opinion and comparisons as many others here too that run them,
@TeCKis300 included.
TLDR;
If i were you, sand running aside since those require a very odd type of tire, i would go with a Toyo or Nitto in 285/65/18 in a C load or above on an 18x9 wheel that you like in a +35 offset that weighs no more than 30lbs. You should also note that since you came from 20s and I 21s with very similar tire diameters if not the same, your speedometer will be almost accurate. We are lucky in this fact above LC owners since they all come with 18s. My gas milage is pretty much 100% accurate too.
This is the longest craziest post ive made but after a year of thinking about this and working on it im finally at a place of peace and wanted to share with this awesome community and actually give something back. If we can make a standalone thread on this for the LX i think it would be super helpful as the inlfux of LXs specially '16+ will only increase from here on out and the 200 never got AHC.
Also cheers and welcome!
