I posed this to some in my club, but thought I might post it to the 'MUD 60 forums, too, in case the discussion might help others down the road (and me before the tire sale runs out on June 1... 
)
I'm trying to decide what tire up-size (and wheel up-size?), if any to do beyond what I already have on my 1983/'86 HJ60. It already has an OME 2.5" lift, and is currently running on BFG KOs in 32 x 11.5 x 15s. For reference comparison with the metric sizes below and my SAE conversions, these are 32" dia, 11.5" wide, and rotate 631 revs/mile. The tires are currently on crummy after-market (unknown make) aluminum wheels (I think they're 7.5" or 8" width?). Though there are four years of 60-series LC in my truck (see signature below ), the driveline and front end geometry/bodywork is all 1986, if that makes a difference.
So here are the options I'm considering (in order of preference) and the couple of questions that it would be great to get anyone's thoughts on (you can just use the option letters and question numbers in your reply, if that helps make it quicker...)
Options...
A) First preference, if it works, is to go up a wheel-size to 16's, and then put BFG KO2s in a 295/75R16 size on them (33.4" dia., 11.6" width, 604 revs/mi), on 16x8 steel wheels (Would be about 1.5" taller, but just about the same width)
B) Maybe a bit narrower than my current tires, and bit less tall than the 295's, but still taller than what I have... 285/75R16's (32.8" dia. and 11.2" width, 615 revs/mi), also on the 16's
C) Or stay with 15" wheels, but with taller, narrower 15's... at 33 x 10.5 x 15 (these are 611 revs/mi), and would also be on steel wheels, but 15"x8"
D) Or stay with my exact current tire size/width and wheel size... the 32 x 11.5's, but in the newer KO2s, and also switch to the 15" steel wheels
Questions...
1) It seems both the 16" wheels and tires have much higher load capacities than the comparable 15's, as the 16" tires are Load Range E versus Range C for the 15's. Does that translate into benefits and/or durability on the trail? (We only ever tow a small camper trailer with the truck, and don't load it very heavily, so I don't need the higher load capacity for that.)
2) I've heard that increasing tire size may require a re-evaluation of the gearing in a 60. I'm not totally sure what gearing I currently have (can I find out with the original VIN it had?). It was originally a Canadian 2H diesel, when new, if that helps. But I am interested whether going up, beyond what I currently have, either the 0.8" in diameter for the 285's, or 1.4" for the 295s, is enough to require any gearing adjustment, if the truck is already oversized at 32's (In owning it for 15 years, now, I have not noticed the truck feeling top-end limited on the freeway with the 32s and the turbo-diesel... ). Any concerns I should have about gearing in a tire up-size beyond what I have?
3) I did a quick, "max turn right & left" clearance check on my tires/wheels today, and I have at least 1"-2" clear of anything on suspension or body at front and rear of each tire, on both sides, with the 32's. The truck has a 2.5" OME lift on it, so I don't think I have any top clearance concerns (and I don't plan on rock-crawling or max-flexing the suspension much if at all). So, would adding 3/4" or less to the radius, while keeping the width about the same or less, seem likely to be okay?
4) Lastly, I've heard of oversize tires maybe putting risky strain on stock driveline components, but I seem to recall that being on really "big" tires... 37's, 40's, etc. And mine was originally a diesel, so would have had any heavier-duty driveline bits that came with that, stock. Any concerns on this for 33's on a 60 with an H55, and stock HJ60 axles/diffs?
5) Any other thoughts on this, outside of what I'm already considering?
Thanks for the time in reading and replying... !
)I'm trying to decide what tire up-size (and wheel up-size?), if any to do beyond what I already have on my 1983/'86 HJ60. It already has an OME 2.5" lift, and is currently running on BFG KOs in 32 x 11.5 x 15s. For reference comparison with the metric sizes below and my SAE conversions, these are 32" dia, 11.5" wide, and rotate 631 revs/mile. The tires are currently on crummy after-market (unknown make) aluminum wheels (I think they're 7.5" or 8" width?). Though there are four years of 60-series LC in my truck (see signature below
), the driveline and front end geometry/bodywork is all 1986, if that makes a difference.So here are the options I'm considering (in order of preference) and the couple of questions that it would be great to get anyone's thoughts on (you can just use the option letters and question numbers in your reply, if that helps make it quicker...)
Options...
A) First preference, if it works, is to go up a wheel-size to 16's, and then put BFG KO2s in a 295/75R16 size on them (33.4" dia., 11.6" width, 604 revs/mi), on 16x8 steel wheels (Would be about 1.5" taller, but just about the same width)
B) Maybe a bit narrower than my current tires, and bit less tall than the 295's, but still taller than what I have... 285/75R16's (32.8" dia. and 11.2" width, 615 revs/mi), also on the 16's
C) Or stay with 15" wheels, but with taller, narrower 15's... at 33 x 10.5 x 15 (these are 611 revs/mi), and would also be on steel wheels, but 15"x8"
D) Or stay with my exact current tire size/width and wheel size... the 32 x 11.5's, but in the newer KO2s, and also switch to the 15" steel wheels
Questions...
1) It seems both the 16" wheels and tires have much higher load capacities than the comparable 15's, as the 16" tires are Load Range E versus Range C for the 15's. Does that translate into benefits and/or durability on the trail? (We only ever tow a small camper trailer with the truck, and don't load it very heavily, so I don't need the higher load capacity for that.)
2) I've heard that increasing tire size may require a re-evaluation of the gearing in a 60. I'm not totally sure what gearing I currently have (can I find out with the original VIN it had?). It was originally a Canadian 2H diesel, when new, if that helps. But I am interested whether going up, beyond what I currently have, either the 0.8" in diameter for the 285's, or 1.4" for the 295s, is enough to require any gearing adjustment, if the truck is already oversized at 32's (In owning it for 15 years, now, I have not noticed the truck feeling top-end limited on the freeway with the 32s and the turbo-diesel...
). Any concerns I should have about gearing in a tire up-size beyond what I have?3) I did a quick, "max turn right & left" clearance check on my tires/wheels today, and I have at least 1"-2" clear of anything on suspension or body at front and rear of each tire, on both sides, with the 32's. The truck has a 2.5" OME lift on it, so I don't think I have any top clearance concerns (and I don't plan on rock-crawling or max-flexing the suspension much if at all). So, would adding 3/4" or less to the radius, while keeping the width about the same or less, seem likely to be okay?
4) Lastly, I've heard of oversize tires maybe putting risky strain on stock driveline components, but I seem to recall that being on really "big" tires... 37's, 40's, etc. And mine was originally a diesel, so would have had any heavier-duty driveline bits that came with that, stock. Any concerns on this for 33's on a 60 with an H55, and stock HJ60 axles/diffs?
5) Any other thoughts on this, outside of what I'm already considering?
Thanks for the time in reading and replying... !
Last edited:
