Road trip Tires: 265 vs 255

[94L C8E]

Howdy all,
I've read a ton on this and for my final push I felt justified in making a thread to ask for specific advice, experiences, etc. TIA regarding KM1 tires on a hwy trip

Long Short of it: I have 265/75/16 uniroyal laredos mounted, which I want to sell - tred decent.
I have 5 used 255/85/16 MT KM1 tires ready to mount, along with counteract balancing system.

Ill be doing a a few hundred this weekend, then a few 1000 miles on hwy in August, not exceeding 65mph, if I can help it.

On current tires, road manners are good; with a canoe on the roof I averaged 16mpg on hwy, and FSRs for a tank, plus city driving too.

Should/ if I switch to the bfg KM1 am I going to really not going to like hwy driving? I read they are harder to track down the road..

Should I just wait until after the road trip or go for it now? Noise levels/ vs tall skinnies are cool factor.

PS counteract says it saves 5% in fuel costs on independent studies of big rigs/ plus 255's are 5% taller and a few % narrower.

Is there any way I'd get BETTER gas mileage on the hwy with the 255's or am I just dreaming?

FWIW I will be siping my tires upon mounting them.

Thanks for any replies,
Damian.

I know I should just do it and then tell u all MY results, but how about it?

 

[etarasoff]

Don't know if the Counteract system is similar to the Centramatic, but if so, you'll also need wheel spacers so that the balancing rings clear the brake caliper.

I have 255/85/16 Cooper STs which are kind of in between an AT and MT. Fantastic looking tire with decent road manners. The main difference, coming from Michelins, was the extra hum on the freeway.

After these tires wear out, I'll probably swap to Toyo AT2s for the quiter ride.

 

[94L C8E]

That's a good call.
I know it's going to be louder than I'd like; but hwy driving is always noisy,
.. See, I have no A/c so windows are open at all times.

One question: is the tire noise even louder with the windows open, or is wind noise overpowering the tire noise at hwy speeds.

Thx

 

[greentruck]

I've run BFG Radial MTs since they came out decades ago. The wind noise will overpower them at highway speeds. The noise will vary depending on the existing wear pattern to a certain degree, but not enough to worry over IMO.

I can tell you you very well might experience a MPG increase. Ours didn't drop anyway. Didn't have the ScanGauge before the KM2s, so can't tell you exactly, but we get about 17 MPG at 70 with the A/C on. Reportedly, in many overseas markets the truck is actually sold with 33s. In any case, the 265s are on the small side, so the truck will look and perform better with the 255s.

Keep in mind that adjusting the PSI with the 255s really transform it, making it quite a versatile tire. Pump it up within reason for highway travel, air down for the trail, about 2/3 in between for a nice ride around town. It's sad that BFG has discontinued this size from current KM2 production.

 

[cartercd]

Let's assume:
-Road trip total is 2,000 miles
- You get 16mpg with your 265 Laredos
- You get 5% increase (16.8 mpg) with the 255 KM1s (and I think this is a stretch, as the benefit of a taller tire is likely cancelled by the added weight and tread pattern/compound not optimized for highway use)

Your gas savings will be = 2000/16 - 2000/16.8 = 6 gallons (23 liters in Canadian-speak, eh).

I would argue that the potential savings of $20 in fuel is not worth it. The Laredos will have better highway manners, shorter stopping distance, lower center of gravity, etc. They were made to be driven on the highway, and the KM1 were made to be driven off-road. I'd wait until you get back to swap tires.

 

[94L C8E]

Keep in mind that adjusting the PSI with the 255s really transform it, making it quite a versatile tire. Pump it up within reason for highway travel

These KM1 tires go up to 80PSI, eh...

in Canadian-speak, eh).

My current within reason, on the Laredos is 43psi. E rated.

What would your hwy tire KM tire pressure be?

also. cartercd, i fully agree with what you're saying, except, once i do switch the tires, say after the road trip;
next summer, i'll be doing just the same driving, with the KM1's - so, i guess i didn't really buy the right tires; i just really wanted the 255 size; and once they're siped, i think stopping distances would be improved in wet conditions anyway, and hopefully road manners, also.. i know what you're saying about the COG and weight, and i do agree that the Larredos are better for the HWY - that's why i'm torn with what to do...

- really i need a spare set of rims...

- oh and 23 X1.279/L is $29.42 - which ain't too bad a savings: 3 summer road trips: boom, payed off mounting costs!

 

[greentruck]

These KM1 tires go up to 80PSI, eh...

My current within reason, on the Laredos is 43psi. E rated.

I'm pretty sure the KM1 are rated the same as the KM2 in equivalent sizes. My KM2 are E rated. I typically run them around 44 psi in town. Hitting the highway, I often take them to 50 psi. I've had KM2 down to about 18 lb, and other have gone to 15 psi, but you're on your own there.

You'd have to have a heck of a load on to go to the max rated pressure. It's going to be rough

More realistically, when towing the trailer loaded, I usually add a couple of psi on the truck rears per recommendation in owners manual for the stock tires, but probably not really needed with E rated tires instead of the stockers.

 

[Heckraiser]

My vote goes to the street tires for road trip.

We can debate all day about whether 255 will yield better MPG, but you state you're already getting 16mpg out of the uniroyals, which is pretty much unobtainable for most of us--i.e. I doubt you'll do any better than that

MPG aside, quieter tire, probably a better ride, leaving less $ on the road as they wear down.

 

[greentruck]

My vote goes to the street tires for road trip.

We can debate all day about whether 255 will yield better MPG, but you state you're already getting 16mpg out of the uniroyals, which is pretty much unobtainable for most of us--i.e. I doubt you'll do any better than that

MPG aside, quieter tire, probably a better ride, leaving less $ on the road as they wear down.

Well, there's no debate that the rolling circumference of the two tires is considerably different and that's where you can find the MPG increase. The 33" tire moves the shift points, RPMs, etc enough to get them in pretty optimal territory. The 265 just doesn't have legs like that. You spin faster, but with 4.11. gears, it doesn't gain you anything and may just burn gas faster.

Logic would seem to suggest that a taller heavier tire would inevitably lead to a MPG decrease. However, almost no one whose made the switch complains about a mileage drop -- and they often note a small bump in mileage. This suggests the theory that Toyota really set the truck up for 33s -- which make a lot more sense with 4.11 gears IMO -- may be correct and would account for the reported gains.

But I didn't go with the skinnies for MPG. I was after off-road performance. Some worry about them being a little slipperier in the wet. I just slow down if required.And they're great road tires...errr OK, let me just say they work as road tires and that works for me -- get me to the trailhead or at least let me imagine I will be there soon. I woulda bought a Porsche if I wanted to fly and fling.

 

[Heckraiser]

Well, there's no debate that the rolling circumference of the two tires is considerably different

No debating that.

and that's where you can find the MPG increase.

Debatable.

 

[94L C8E]

Sage advice all. And healthy debate.

Now I really don't know which way to go.

I thought I did for a second there - was going to stick with the HWY 265's.

I'm in theory all keen to mount the 255's.

One thing, mine are KM1 - I think they're heavier and likely louder..?
I will be siping and this may achieve more km2 behaviour/ snow performance, etc..

K. Bottom line: my passengers are musicians - not overlanders, I've got them a good loud stereo, which will be blasting bluegrass anyway. will the tire noise drive them nuts on a 8 hr hwy drive - I'll be fine; like the rest of us addicts..

 

[DARKNESS]

not exceeding 65mph

This probably has more to do with your mileage than anything.

Probably either would be fine. I have siped KM2's on my Tacoma. They're for sure not a road tire and they're terrible on snow an ice, but I drive it on long highway trips sometimes and I can't say they bother me. Not sure about the KM1.

I just put 265 Michelin LTX MS2's on my 80 after considering 285's. My main reason was that I don't plan to wheel hard and I have seen a ton of posts about 285's making high altitude mountain passes difficult. Not sure if you'll be at altitude, but that may be a consideration.

 

[Whileemptyheadsdream]

Extra set of rims, switch back and forth on the 8 hour trip. Let the band decide.

 

[Qball]

Best MPG I found on highway is 35s, 65pmh is at 2100rpm.

 

[greentruck]

Best MPG I found on highway is 35s, 65pmh is at 2100rpm.

Yep, 2100 rpm is the sweet spot for best mileage regardless of tire diameter -- at least anything likelt to be fitted to an 80 and legal to drive on the road. I don't recall the math exactly, but for the 33s it has to be around 62 or 63 mph? That, BTW, as in 100 kilometers per hour, is a commonly encountered speed limit in many countries, so it makes sense to gear the 80 with 4.11s to hit that mark.

That would put 2100 rpm on 265s down around 59 or 60 mph maybe? I dunno, check my notoriously bad seat of the pants math That's why many people discover equal or slightly better mileage with the 255s. Your engine isn't spinning so fast for what's legal and reasonable to get down the highway.

I can definitely see Darkness's concern if I lived in Colorado and would be living that far above sea level. Haven't been back to Colorado since copping the 80 but hope to rectify that and do some "testing." And we'll be taking the trailer, so this could get interesting. I will report back how the truck handles altitude on 33s. Some say they're fine on 35s, which I find a bit questionable. I've been back and forth enough, you always miss the power if you come from the Midwest, maybe not so much if you're already used to it?

 

[94L C8E]

Well, after a 400 mile trip; on one tank
I'm super glad I kept the 265's hwy tires on. It was wet, and I'd be scared to have been hydro planing all over. ..
... Now I realize that MT tires will need grooving and siping before any road trip.
It's been a drought here, and boy did it rain this weekend.

Good times.
Guess I'm getting the ideal tire groover. And ill wait until fall to mount the mud terrain 255's

 

[greentruck]

Give yourself some time and opportunity to get used to how the MT's handle. One has to take a little care here and there, but it's not too big a deal. There's a lot of scary stories out there. My own experience is that driving stupid is what usually gets people into trouble and results in those sorts of stories. It's also important to realize it's a rather specialized tire. If you want high performance strictly on the road, then there are better tires. But that's not what an MT should be expected to deliver.

 

[LINUS]

Just from the pure aspect of running what you know is familiar & the road manners, I'd stay on those - that way any odd sounds you hear aren't the tires but something you really know as a new sound.
Beyond that the handling characteristics you know.

If you're really feeling fancy maybe rotate 'em prior to trip- even out any odd treads?