Ride Quality: BFG KO2’s, 20 vs 18 vs 17” ?

[DaveInUtah]

Have 20” KO2’s (D rated) on my LX570 and the ride quality kind of sucks. Wondering if going to 18 or 17” (and still doing KO2’s) would help much. Had a tire guy tell me it wouldn’t make much difference due to the 4 ply sidewall, but I wanted to get the opinions of anyone who has direct experience? (Yes, I’m aware that 17/18’s are better for off road too, and aware of the towing/handling trade offs. Wondering specifically about ride quality)

I know it would be an improvement, but for the money, am wondering if it would be “a little better” or “a lot better.”

Thanks in advance.
Dave

 

[luke27617]

Riding on 20" as well but went one size up. At recommended 50 PSI they were terrible. Currently riding at 42PSI and the ride is acceptable.

 

[DaveInUtah]

Yeah, I've even tried airing down to 35 psi and the ride still ain't great

 

[luke27617]

Yeah, I've even tried airing down to 35 psi and the ride still ain't great

I went one size up as I was hoping the extra side wall will help but definitely I was wrong. The ride is not the best, but they at least look great . I am at almost the same side wall (.5" diff) as original size on 18". Going down in size of wheel I don't think will make much of a difference. Go for looks or comfort as Defenders which I had before.

 

[gaijin]

Have 20” KO2’s (D rated) on my LX570 and the ride quality kind of sucks. Wondering if going to 18 or 17” (and still doing KO2’s) would help much. Had a tire guy tell me it wouldn’t make much difference due to the 4 ply sidewall, but I wanted to get the opinions of anyone who has direct experience? (Yes, I’m aware that 17/18’s are better for off road too, and aware of the towing/handling trade offs. Wondering specifically about ride quality)

I know it would be an improvement, but for the money, am wondering if it would be “a little better” or “a lot better.”

Thanks in advance.
Dave

It's hard to answer definitively without specific tires/sizes, but for the sake of discussion, let's use some example cases:

Let's assume you have the LT285/55R20/D 117/114T BFG KO2 (Overall diameter 32.4" / 6.2" sidewall height) tires on your LX570. The Recommended Cold Tire Inflation Pressure (RCTIP) for this tire on your LX570 is 43psi F/R.

One 18" equivalent to the 20" tire would be the LT285/65R18/E 125/122R BFG KO2 (Overall diameter 32.6" / 7.3" sidewall height) tires. The RCTIP for this tire on your LX570 is 37psi F/R.

A 17" equivalent to the 20" tire would be the LT285/70R17/E 121/118R BFG KO2 (Overall diameter 32.8" / 7.9" sidewall height) tires. The RCTIP for this tire on your LX570 is 35psi F/R.

In principle, the more sidewall and the lower the tire pressure the "softer" the ride will feel.

I have been running the LT285/70R17 BFG KO2 tires on my LC200 at the RCTIP of 40psi for a long time and find the ride very comfortable.

Having said all that, I would expect the LT285/70R17/E 121/118R BFG KO2 tires with 7.9" sidewall at 35psi on your LX570 to have a much better ride quality than the LT285/55R20/D 117/114T BFG KO2 tires with 6.2" sidewall at 43psi.

If nothing else, you now have more data on which to base your decision.

HTH

 

[DaveInUtah]

Thanks fellas, appreciate the replies. Should have mentioned, they are LT275 60 R20, D rated.

Looking at 17” options, think that C vs E rating makes much difference in ride quality?

 

[eatSleepWoof]

Looking at 17” options, think that C vs E rating makes much difference in ride quality?

Not just a difference, but a big difference. If ride comfort is a significant concern and you're not on rough, rock-crawling trails every weekend, I'd suggest grabbing a set of 33" P-rated AT tires such as General Grabber APT in 275/70/18. Roughly the same height as what you're on, slightly narrower, way more comfortable, and at only 42lbs, significantly lighter than any of the options discussed above.

 

[DaveInUtah]

Hmm, but if I stick with LT tires, they also come in both C, D, and E ratings. Big difference among LT tires?

Not aware of any P rated tire that’s as puncture resistant as the LT tires, but is this an exception?

 

[TeCKis300]

I know you're trying to tweak wheel sizing to gain ride quality. Not dissuading you from that, but perhaps another variable to play with.

I'd re-examine the want for KO2s. While a great benchmark tire, they lean to towards the more aggressive end with more durable construction and firmer rubber compound (read stiff). I recall an article of Ford developing the Raptor, was initially provided from BFG, LT KO2s in Load Range E. Engineers decided these were too harsh, and being a large enough customer, and asked BFG to manufacture Load Range C versions that did not exist prior. This does support some of the comments earlier that Load Range can have a large impact. Unfortunately, in the aftermarket, you'll rarely see great selection of load ranges, and is often the case that only the higher load ranges are available for particular sizes. Which bring me full circle to suggest perhaps another tire?

 

[DaveInUtah]

I believe I saw 17’s available in load C for KO2’s?

 

[bloc]

I run p-metric 285/70r17 toyo AT2s on rock warriors currently. Previous setup was e-rated 285/65r18 ko2 on stock 2013 cruiser wheels.

I lost some weight with this setup (back to stock wheel and p-metric tire total), gained a half inch of sidewall between the road and rim, and was able to lower inflation pressure over 10psi. The difference in ride quality was nothing short of dramatic.

C-load LT tires will save some weight but still require higher pressure to avoid damage, which is where I believe the bulk of the ride quality issues come from. “Tire spring rate”

 

[DaveInUtah]

So C rated tires require more tire pressure and thus have a harsher ride than E rated, despite the stronger ply?

 

[DaveInUtah]

Also, HTH, you mentioned you run LT285/70R17 BFG KO2 at 40psi, are these the same spec tires as the 17’s you mentioned I could run at 35psi? If so, why the difference in pressure?

 

[bloc]

So C rated tires require more tire pressure and thus have a harsher ride than E rated, despite the stronger ply?

No, similar pressure to e-load, but significantly more than p-metric.

The stronger ply is actually part of why they need more pressure. Thicker rubber and structure generates more friction and heat. So you need to add pressure to reduce flexion and keep heat at bay.

P-metric is so much less substantial that they operate well with significantly less pressure. This is also why they usually get so much better mileage.

And as for flats.. I did get one sidewall tear that probably would have torn an LT-E as well. Otherwise no issues, though my whole setup acknowledges the 900+ road miles I usually do before hitting the trails.

 

[gaijin]

So C rated tires require more tire pressure and thus have a harsher ride than E rated, despite the stronger ply?

No. For tires of the same size, E-Rated and C-Rated LT-Metric tires will require exactly the same RCTIP.

HTH

 

[gaijin]

Also, HTH, you mentioned you run LT285/70R17 BFG KO2 at 40psi, are these the same spec tires as the 17’s you mentioned I could run at 35psi? If so, why the difference in pressure?

LC200 and LX570 have different tire pressure specs because the suspensions are different - you'll have to ask Mr. T why he engineered them this way.

For my LC200, 40psi is the correct RCTIP for the LT285/70R17 tires. The same tires on your LX570 have a RCTIP of 35psi.

HTH

 

[Madtiger]

Love my ride on LC with stock 18” rims and stock size KO2 at recommended pressure (46 psi).

 

[TeCKis300]

Also, HTH, you mentioned you run LT285/70R17 BFG KO2 at 40psi, are these the same spec tires as the 17’s you mentioned I could run at 35psi? If so, why the difference in pressure?

@gaijin does his pressure recommendations from the perspective of load limits based on the stock fitment and pressure spec. A solid and always safe way to translate to other tire sizes and specs.

The reality is there's some wiggle room in inflation pressure to adjust for other factors and preferences as seen in the variation between the LX and LC. Including adjusting for comfort. I'd have no qualms using the lower of the two RCTIPs between the two.

The stock pressure spec is one that accounts for the full extents of the vehicle performance envelope, including full payload on the hottest of days. Day to day unladen use isn't that, so some degree of less pressure is okay.

 

[eatSleepWoof]

Not aware of any P rated tire that’s as puncture resistant as the LT tires, but is this an exception?

There is entirely too much misinformation and outright bullsh!t posted online about puncture resistance of LT tires. I'm confident that at least 60-70% of such posts are simply people who are trying to justify their own purchases of bigger tires as some sort of "need" for "safety," versus the truth of it being a "want" and a toy (for most).

The biggest advantage of LT-rated tires, and specifically higher load-ratings is just that: load rating, or the ability to carry weight... the kind of weights the 200 series will never, ever see. There are many variables between tires and tire manufacturers, and while in certain cases and certain scenarios there is likely truth to the "more puncture resistant" notion, for most people it's almost certainly to be a moot point.

You can puncture any tire, and tear any sidewall. I don't believe that the average person will see any "puncture resistance" benefit of an LT A/T tire vs a P-metric A/T tire.

Now, if you're going to take Michelin Pilot Sports on miles of shale, yeah, you're likely going to have a problem. But if you run an A/T like the one I suggested above, and drive random FSRs with the occasional obstacle, LT tires will offer you no benefit, but will simultaneously cost you comfort, economy, performance, and wear & tear.

 

[Rando Kuruza]

LT tires ride rough. I have an LX570 with 275/60r20 I have them inflated at 41 is that right? I’m not sure I think I got that number from gaijin in another post. But they are wearing evenly. When I tow the airstream I go 55 psi in the back 4300 lbs on my rear axle. And 46 psi on the front 3350lbs on my front axles... Boy it rides rough with those pressures. I have d rated BFG KO2’s tires because I tow and we do go on rocky desert trails and Rocky Mountain trails... but if I didn’t do either p metrics ride sooooo much better.

Different car but I run 275/70r18 e-rated on my lx470 at 40psi they still ride pretty rough...

honestly though your body on frame, with truck tires on 20’s it’s going to ride like a truck. Go 17’s with p metric highway tires it will be buttery smooth.