Thoughts on Sizes for BFG KO2s on stock wheels?

[Swayor]

I am considering replacing the stock Dunlops on my new 2016 LC with KO2s. I had these on our LR4 and really like them. 2 questions. Sizes and "when" to do this. Input is welcome. (Not interested in input on other tire brands/models as I have already made that decision.)

First, my major drivers on size are 1) Modest off road driving but plenty of sharp-ish rocks on these Colorado Trails. 2) We pull a 6,000# trailer. For these two reasons I'm leaning towards the E-rated LT models which is what we had on our LR4.

Size options I'm considering. Primarily the 285/65R18. Same width as stock. A tad more height (32.5" vs 31.5"). E-rated. I could also consider the 275/70R18 if I wanted it bit more height but I would lose some width and I'm not sure 0.35" of lift is that big a deal. I could also consider a D-rated 285/60R18 if the other options will give me fit issues.

My questions about sizing are whether there are any fitment problems with the 285/65R18? I don't want any rubbing. And I want to be sure the spare (same model/size) will fit in the normal spare tire spot underneath.

As for timing, I'm wondering how long I can use the stock Dunlops. I don't know anything about them. In a couple weeks we'll be towing our trailer and then doing some off road. Are the new Dunlops good enough for now? They are D-rated, not LT tires. That is probably my most significant concern is sidewall strength when off road. If they are good tires for now I'll put another 10K on them and put the KO2s on in the Spring.

Thoughts?

 

[Swayor]

stock 18"wheels, 2010. KO2's 275/70/18 put them on just a few days ago. They are great. No rubbing, spare fits spot on. Also a very easy tire to find if you ever have an issue.

 

[gaijin]

Thanks! I hadn't seen "the book" so for me you are the book. . I do think I need to be a bit higher due to altitude? I live at 6,000' and spend a lot of time in the mountains.

You're welcome. Altitude makes no difference in your case. We're talking cold air pressure psig - gauge pressure. Stick with 41psi F/R.

HTH

 

[Markuson]

Should be super smooth ay any speed. Sounds like they did a really poor balance job...

 

[Tommy Dwyer]

@Swayor No rubbing on the 275 70 18? No lift?

 

[Swayor]

Nope. Bone stock. Tire is a bit taller and not as wide so It just makes it. Punch in tire size comparison "Google search" It shows the difference in sizes and compares revs per mile, etc. Maybe 1 less MPG, maybe 1-2 off on MPH showing. They feel good too, maybe just new tires always feel good. Discount tire did it, recommended them. I went in to buy same stock 285's, but I knew these would work because I already did my home work. Tons of stuff on IH8MUD. Did some wheeling already, so for me it's confirmed.

 

[Tommy Dwyer]

View attachment 1325887 View attachment 1325888 View attachment 1325889 Nope. Bone stock. Tire is a bit taller and not as wide so It just makes it. Punch in tire size comparison "Google search" It shows the difference in sizes and compares revs per mile, etc. Maybe 1 less MPG, maybe 1-2 off on MPH showing. They feel good too, maybe just new tires always feel good. Discount tire did it, recommended them. I went in to buy same stock 285's, but I knew these would work because I already did my home work. Tons of stuff on IH8MUD. Did some like wheeling already, so for me it's confirmed.

Fantastic, thanks! I'm in the market for new shoes, and have been searching the forum / web a bit. I had pretty much decided on 285 / 65's to be on the safe side as I'm not just ready for a lift (yet), although I will be doing the spacers soon to level up the front end a bit. Another plus on the 275 / 70's is that they seem to be a bit less expensive Thanks again!

 

[Swayor]

Yesss. If you really want to save a little $, go for the ridge grapplers. I think on road ride is better with KO2's though. Send me a pic / review once you are leveled. It sounds like we are thinking the same way right now.

 

[Dan Higgins]

Thanks, Everyone. I went back to Discount Tire (sort of messed up the first half day of my vacation) and they said one of the rear tires had "thrown" the weight they had put on for balancing. Whatever. But they did rebalance all of the wheels and it ran great the rest of the day. I will check the air in the morning (cold) and drop the fronts to 41 and the rear to 45. I had always thought that when running an LT tire with a max PSI of 80 I should run them higher. But I guess that additional margin if for when you run heavier payloads (e.g. When you use them as a truck would). I don't run that heavy without the trailer. 1-2 adults. Some gear but no rear seats. Anyway, I'll lower them and see how they feel.

 

[Tommy Dwyer]

Yesss. If you really want to save a little $, go for the ridge grapplers. I think on road ride is better with KO2's though. Send me a pic / review once you are leveled. It sounds like we are thinking the same way right now.

Will do, thanks. And sorry for barging in on your thread @Dan Higgins !

 

[gaijin]

Thanks, Everyone. I went back to Discount Tire (sort of messed up the first half day of my vacation) and they said one of the rear tires had "thrown" the weight they had put on for balancing. Whatever. But they did rebalance all of the wheels and it ran great the rest of the day. I will check the air in the morning (cold) and drop the fronts to 41 and the rear to 45. I had always thought that when running an LT tire with a max PSI of 80 I should run them higher. But I guess that additional margin if for when you run heavier payloads (e.g. When you use them as a truck would). I don't run that heavy without the trailer. 1-2 adults. Some gear but no rear seats. Anyway, I'll lower them and see how they feel.

Good to hear DT got the balance right.

Just to be clear, for on road use you should run 41psi Front and Rear. Even when towing, 41psi in the rear should be fine unless you notice significant sidewall bulging - then you could put it up to 45psi while towing, and back to 41psi when not towing.

At 41psi in the rear you are already above the rear GAWR (Gross Axle Weight Rating) of 4300 lbs for your truck.

HTH

 

[Markuson]

Good to hear DT got the balance right.

Just to be clear, for on road use you should run 41psi Front and Rear. Even when towing, 41psi in the rear should be fine unless you notice significant sidewall bulging - then you could put it up to 45psi while towing, and back to 41psi when not towing.

At 41psi in the rear you are already above the rear GAWR (Gross Axle Weight Rating) of 4300 lbs for your truck.

HTH

Agree.

After running mine a little lower...I was convinced by others on mud to run 40-41, and I'm quite happy with it.

 

[Dan Higgins]

Awesome. I'll have an even smoother ride! Didn't get to it this morning as I was on the road at O dark 30 to catch the sunrise on the Aspens on Independence Pass here in CO. But I'll take care of it and let you all know. I'll also be towing tomorrow.

 

[Dan Higgins]

I just wanted to follow up and say that I am loving the KO2s with the PSI at 41 (thanks gaijin!) Ride is great. I'll raise the rear to 45 when towing. I carry a compressor so not hard to make adjustments. What I have found interesting is that the TPMS system/sensors read the PSI about 1.5-2 lbs low. I have a couple different digital pressure gauges. One reads about a half lbs below the other but they are consistent. They read 41 or 41.5. The TPMS system reads 39 on each tire. (I don't know if earlier models did this but with the 2016 you get a pressure reading for each tire and for the spare.)

Again, thanks for the help.

I am loving this truck!!!

 

[gaijin]

Good to hear you're happy with your setup - thanks for the feedback.

I have this pressure gauge:

Specs say it is accurate to 0.1% - see manufacturer's data page here: 99.99 PSI DIGITAL AIR PRESSURE GAUGE - Intercomp Racing

Using this gauge, and comparing the pressures to my TPMS, I also find that the TPMS reads about 1 or 2psi low - hard to tell for sure because the onboard TPMS readout is in whole psi.

I'd trust your gauge and just use the TPMS readings as a reference.

HTH

 

[Dan Higgins]

Good to hear you're happy with your setup - thanks for the feedback.

I'd trust your gauge and just use the TPMS readings as a reference.

HTH

Thanks for the confirmation. That is what I decided to do. If I know that they are always a couple lbs low and that they are consistent then I can handle that. I just needed to find something other than the TPMS system to tell me the PSI. The confusion started because I would go to the Discount tire just down the street and have them put in 41. Then I would look at the TPMS and it read 39. I would go back to DT and we would go through it again. So I picked up the digital gauges and found that they agreed with each other and with DT within a half a lbs. So I am just assuming that the TPMS is off or biased or whatever. I've also determined where I need the needle to be on my VIAIR compressor's gauge (analog) to get to 41 PSI or just over. This will help if I drop them down when going off road. Thanks again!

BTW, is there a publicly available chart that shows the recommended PSI for increasing axle weights? It would be nice to know that if I drop 600 lbs of tongue weight from my trailer on the rear axle then I should increase the PSI to whatever. I know you said 45. I'm just wondering if there is a chart.

 

[gaijin]

BTW, is there a publicly available chart that shows the recommended PSI for increasing axle weights? It would be nice to know that if I drop 600 lbs of tongue weight from my trailer on the rear axle then I should increase the PSI to whatever. I know you said 45. I'm just wondering if there is a chart.

I think we have been talking past each other on this point. The 41psi is recommended for ALL weight, whether towing or not, up to the GAWR of your truck. Whether you have no extra weight or 600 lbs on your tongue, the recommended tire pressure is still 41psi.

What I recommended was that IF YOU NOTICE SIGNIFICANT TIRE BULGE WHILE TOWING, then you MAY increase the rear tire pressure to 45psi, but THERE IS NO REQUIREMENT TO DO SO.

There is indeed a chart for the relationship of tire pressure to Load Limit for your tires, that is the chart in the Tire and Rim Association's Yearbook from which I derived the 41psi recommendation. That 41psi covers all loads up to the limit of the truck. To put it another way, if you need more than 41psi, then you are exceeding the GAWR/GVWR of your truck - that's no bueno.

HTH

 

[Dan Higgins]

OK. Got it. Even better. No need to adjust PSI is one less thing to worry about. No I'll only be changing when I go off road. Thanks. And, no, I won't be exceeding the GAWR/GVWR of the truck.

 

[gaijin]

 

[Dan Higgins]

I think we have been talking past each other on this point. The 41psi is recommended for ALL weight, whether towing or not, up to the GAWR of your truck. Whether you have no extra weight or 600 lbs on your tongue, the recommended tire pressure is still 41psi.

What I recommended was that IF YOU NOTICE SIGNIFICANT TIRE BULGE WHILE TOWING, then you MAY increase the rear tire pressure to 45psi, but THERE IS NO REQUIREMENT TO DO SO.

There is indeed a chart for the relationship of tire pressure to Load Limit for your tires, that is the chart in the Tire and Rim Association's Yearbook from which I derived the 41psi recommendation. That 41psi covers all loads up to the limit of the truck. To put it another way, if you need more than 41psi, then you are exceeding the GAWR/GVWR of your truck - that's no bueno.

HTH

OK. Heard back from BFG. Now I'm really confused. Their answers are very different. Here is what I wrote them and they said in their answer. Note that although they promised to send me a chart, no chart was attached. I have replied to them requesting that chart. If the difference were just a couple of PSI I would be OK. But they are stating a minimum of 55 PSI! (My email to them is shown in green. Their reply is in Blue.)

I have new 285/65R18 E-rated TA KO2 tires on my 2016 Land Cruiser. The curb weight of the Land Cruiser is 5,765 lbs and normally the only added weight is 2 adults and maybe 150 lbs of gear. But on occasion we will be towing a travel trailer with a tongue weight (weight added to the rear axle of the Land Cruiser) of between 650 and 700 lbs. What PSI should I use with these tires? (The stock tires were P-rated and had a PSI setting of 33.) I know these KO2s have a max of 80 PSI. But I will never need to do anywhere near that.

What PSI would you recommend for those to vehicle weights? Better yet, can you send me or point to a chart that shows how much air I should put in the tires for different weights (or what weights are supported by varying PSI) for those 285/65R18 KO2s?

Thanks,
Dan
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Based, on the information provided, the actual recommended tire size for your vehicle is the 285/60R18 at 33 psi. After conversion, the minimum recommended tire pressure will be 55 psi on an empty vehicle. Considering the load and the trailer, you may increase to 60 psi depending on your ride comfort. You can not add too much as the tire may be overinflated and degrade not only the ride quality, but also the tire wear.


I have attached a load/pressure chart for you to use.