What tires y'all recommending? (1 Viewer)

[Bud_Dude]

Make sure the tire size is a good match for your gearing. My experience with tires on 80 series:

I had 285/75R16 tires on my 94 with factory gearing. I was happy with it as far as I can remember. If I needed extra power climbing hills I would turn OD off.

My 97 was regeared to 488 when I bought it, and came with 315/75R16 tires. It was a great match, plenty of power when needed. On the grades I would turn off the OD and could cruise all day at 2800-3000 RPM and ~65-70 mph (going on memory here). Very happy with that combo.

When I needed new tires I thought I would try something a little smaller and got 295/75R16 tires. Hated them. That size just never worked well with the gearing. It was ok on flat ground I guess, but going up grades it had no power with the OD on, and the RPMs were too high with the OD off at my preferred cruising speed, forcing me to slow down or wind out the motor at 3500+ RPM.

Again, going on memory, so the exact numbers are a little fuzzy, but I do remember that 285 w/ stock gears were fine, 315 w/ 488 gears were fine, and I didn't care for 295 with 488 gears. If you are ok with driving slower up grades in a lower gear, maybe the 295s will work for you. They just didn't work for me.

That's just my experience, yours may be different.

Interesting. I have 295/75R16 Nitto's on there now and just returned home from a 2500 mile trip to and around Colorado. The I-70 east climbs from Glenwood Springs to the Eisenhower tunnel were killer, dropping into 2nd gear at times and roaring up to and over 4000 RPM while seemingly crawling up the hill. This on a freshly rebuilt engine. Often I found turning OD on and off had little to no effect at all, maybe a couple RPM, other times it seemed to help. Perhaps that's a sequence of operations thing... ie maybe disengage OD before getting on to the gas? Maybe should play with / test that some more...

Obviously the goal being to cruise up hills at 60-65 while staying nicely below 4000 RPM, but not run higher RPMs on flat land by going smaller on the tires with 488s... More often than not it seemed I was at 45 going up the hill at 4000 RPM, which I really don't like to do. I really doubt that increasing the tire diameter from 33.4" to 34.6" (3.5% larger in terms of radius ergo torque requirement) would better position the engine in the peak power band for increased uphill climb performance; but maybe... it just doesn't seem intuitively likely. Not sure how this 1FZ-FE engine torque / power curve with its relatively flat torque factors into the situation, but it sure seems that it's really just a matter of needing more overall power to overcome the vehicle weight (with bumpers, winch, roof rack and camping gear) and speed desire going uphill. We need transmission engineer Frank @elripster to chime in to explain that (to me anyway). Larger tires to me just seem like they'd be even harder to go uphill on...

Aside from increased cost for 315's I have no issue going bigger if they would somehow make the truck climb hills better on the highway.
My wife, on the other hand, will complain mightily if the truck gets any harder for her to climb in to; she's already after me to lower it a bit...

 

[sdnative]

In the 80, I only have experience with the local grade going out east to AB, grade going up Cajon Pass, and going up from Phoenix to GC/Flagstaff. Never took the 80 to CO so I can't speak to the tire/gearing dynamics there.

I'm not saying that 315s make the truck climb hills better, just sharing my experience with the local grades and going up towards Flagstaff with my setup.

From what I hear the I-70 going up to Eisenhower tunnel is brutal and rough on any vehicle so maybe that's not a good comparison.

 

[elripster]

315s won't help climb faster in most cases except maybe were you are tached out is say 2nd gear but can't pull in 3rd. You might get an MPH or two. They will actually increase road load and might just slow you down a little. But... in CO you are at elevation and so the truck is just going to be down on power vs here in San Diego. I think you nailed in that if you want to climb those hills faster, you need more more power so you need forced induction or more displacement. The engine is putting out energy as fast as it is able and the truck's climbing speed is suggesting it just doesn't have the power, at least not at elevation.

What turning the OD off does do is cause the torque converter to lock up so can reduce transmission temps since it's not shearing oil in the torque converter.

If you go with a snorkel (can't recall if you have one) and cat back the exhaust you can get some more of the post 4k RPM torque but that's not a comfortable place to cruise for certain.

Frank