5th tire in rotation?? (1 Viewer)

gregnash

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So question to everyone....
Purchased my 98 100 series this time last year (drove home on the 19th) and when I got it the guy had put practically brand new 285-75/16 Falken Wildpeak AT3W.
However, the spare is still an original and thus is OLD and doesn't match size (and pretty sure it is flat as well).

Since purchase of the truck I have put just over 10k miles on it in the year of ownership (purchased at ~192k now at ~202,700) and pretty sure that the tires has approximately 5k miles on them already. So at this point, is it still good to throw a 5th NEW tire into the rotation or should I just buy something CHEAP that is same size as an emergency only tire?. The Falkens are running about $230 locally plus install and whatnot, whereas I can get something that is an emergency tire for about $160.

Thoughts?
 
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Should be fine to throw a new 5th tire into the rotation. If you want to get it to the same miles as the others with 5000 miles on them just put it into the rotation at a point where it is last to make it to the spare spot or have it skip the spare spot one round. You should be fine though.
 

80t0ylc

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So question to everyone....
Purchased my 98 100 series this time last year (drove home on the 19th) and when I got it the guy had put practically brand new 285-75/16 Falken Wildpeak AT3W.
However, the spare is still an original and thus is OLD and doesn't match size (and pretty sure it is flat as well).

Since purchase of the truck I have put just over 10k miles on it in the year of ownership (purchased at ~192k now at ~202,700) and pretty sure that the tires has approximately 5k miles on them already. So at this point, is it still good to throw a 5th NEW tire into the rotation or should I just buy something CHEAP that is same size as an emergency only tire?. The Falkens are running about $230 locally plus install and whatnot, whereas I can get something that is an emergency tire for about $160.

Thoughts?
If I'm reading you correctly, your Falkens have the 10K (your miles) + the 5K you estimated they had when you purchased, so say, 15K on the tires now. I'd measure existing tread depth on your Falkens and compare to what a new one is, because that is what is important if you want to run the 5 tire rotation, assuming all are the 285-75/16 size. Tire wear is so subjective, you can't really say that 15K miles is like new. If it were me, 4 tire rotation with a "same size" emergency only spare until the Falkens wear out and then buy 5 new tires and drop back into the 5 tire rotation routine would be fine.
 

gregnash

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If I'm reading you correctly, your Falkens have the 10K (your miles) + the 5K you estimated they had when you purchased, so say, 15K on the tires now. I'd measure existing tread depth on your Falkens and compare to what a new one is, because that is what is important if you want to run the 5 tire rotation, assuming all are the 285-75/16 size. Tire wear is so subjective, you can't really say that 15K miles is like new. If it were me, 4 tire rotation with a "same size" emergency only spare until the Falkens wear out and then buy 5 new tires and drop back into the 5 tire rotation routine would be fine.
See that was what I was kinda thinking. I got another rotation coming up in a few months so I will have DT measure and let me know. Ultimately, when these do run out I plan to upgrade the rims to something larger than stock 16s so will likely have to throw a 5th rim in there as well (with eventual plan to have bumper with spare swing out).
Hence why I was thinking mainly of dumping the cheapo spare on there as these tires have seen mainly on-road usage but do happen to have club runs in rocky terrain about once a month.
 
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I have 285/75R17 Toyo MT’s. I rotate the spare in best as I can. I think I did 12000 km one trip
and after that realized I’d forgotten to add the spare in. I just put it on the drive wheel in back
didnt give it another thought. Don’t think it has any problems. Couple trips later can’t tell which one
that one was.
 

80t0ylc

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I have 285/75R17 Toyo MT’s. I rotate the spare in best as I can. I think I did 12000 km one trip
and after that realized I’d forgotten to add the spare in. I just put it on the drive wheel in back
didnt give it another thought. Don’t think it has any problems. Couple trips later can’t tell which one
that one was.
OP's rig is a 100 which, IIRC, is full time - like my 80. Going by your sig, it looks like you're running a 60 which IIRC is not full time. Full time rigs are more sensitive to needing all four tires to be very close to same size, to avoid excessive drive train wear and issues. Even with full time, I might chance missing rotating in the spare a time or two, depending on conditions. It may sound a little OCD, but running full time rigs mostly on high traction surfaces, much of it at higher speeds, it pays dividends to be sure your tires and spare, if run, are matched as closely as possible.
 

80t0ylc

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See that was what I was kinda thinking. I got another rotation coming up in a few months so I will have DT measure and let me know. Ultimately, when these do run out I plan to upgrade the rims to something larger than stock 16s so will likely have to throw a 5th rim in there as well (with eventual plan to have bumper with spare swing out).
Hence why I was thinking mainly of dumping the cheapo spare on there as these tires have seen mainly on-road usage but do happen to have club runs in rocky terrain about once a month.
You should be good, epecially if flats are rare for you and your locale. In high risk situations, like severe off road travel or visiting construction sites or areas with a lot of road hazards, it might be a different story. LT tires, like most SUV's run, usually have deep enough tread to avoid a lot of flats that purely passenger car tires suffer, if the LT tire tread wear is less than 50%.
 
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OP's rig is a 100 which, IIRC, is full time - like my 80. Going by your sig, it looks like you're running a 60 which IIRC is not full time. Full time rigs are more sensitive to needing all four tires to be very close to same size, to avoid excessive drive train wear and issues. Even with full time, I might chance missing rotating in the spare a time or two, depending on conditions. It may sound a little OCD, but running full time rigs mostly on high traction surfaces, much of it at higher speeds, it pays dividends to be sure your tires and spare, if run, are matched as closely as possible.
Maintenance and parts costs might be reduced with part time kit. I do run a 60. It was a decider
when I looked at 60 and 80. That and the width. Curious as to why guys don’t install part time kits more
often.?
 
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I guess it depends on your measurments and how much wear the tires have after 15,000 miles. Let me preface the following as just thoughts/opinion and that I have no expertise in this area at all and could be way off. That said I shouldn't even be posting but would like to see how how far off base I am in my thinking or if we have all succombed to the land cruise OCD that we have become so nit picky about theory that has no real world tangible benefit.

I have a set of AT tires on my 80 that have about 100,000 miles on them and still have plenty of tread left. I doubt there would be much noticeable difference in measurments on my tires after 15,000 miles. I would guess there is less than 1/32 inch difference between an new tire and what you have on there - I could be very wrong in that assumption though. Full time 4wd vehicles aren't locked and have open diffs in everyday driving. If that small of a fraction of diameter made such a huge wear on our drive trains we would be afraid to take any turns on the road since the strain on the drive train would cause it to fail prematurely. Each turn we make has a pretty significant rotation difference between the inner and outer tire and between the rear and front tire for that matter. We don't drive around being paranoid doing everything possible to avoid turning to prevent wear because engineers have accounted for that with our open diffs. All that to say I think the open diffs could accomodate a small difference in tire diameters and would guess that the difference in a cheap tire of the same manufactured size would actually measure significantly different that a new tire of the same size from the same manufacturer even when comparing it to the used tires you have on.
 

e9999

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OP, a small diameter difference should be fine if you are not locked on a sticky surface, I think. I would go with a matching 5th personally. Especially given the small difference in cost you mentioned. Just leave it on for a while without rotating it out and in a couple of years you should be close. The nice thing about the 5th is that if you had only 4 worn ones say and then have a terminal blowout, then getting a new one to match would be more of a problem at that point and you may need to replace the other 3 too, so a bigger loss. And some tires or sizes are just difficult to find in some places, especially after a while.
I do full rotation with 5 on mine and I still see differences in tread depth. Probably mainly to do with front vs back or alignment issues. To alleviate that a bit I measure each time and rotate out the worse one rather than sticking to a fixed pattern.
 

gregnash

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OP, a small diameter difference should be fine if you are not locked on a sticky surface, I think. I would go with a matching 5th personally. Especially given the small difference in cost you mentioned. Just leave it on for a while without rotating it out and in a couple of years you should be close. The nice thing about the 5th is that if you had only 4 worn ones say and then have a terminal blowout, then getting a new one to match would be more of a problem at that point and you may need to replace the other 3 too, so a bigger loss. And some tires or sizes are just difficult to find in some places, especially after a while.
I do full rotation with 5 on mine and I still see differences in tread depth. Probably mainly to do with front vs back or alignment issues. To alleviate that a bit I measure each time and rotate out the worse one rather than sticking to a fixed pattern.

Ok so I went and had them measured and inflated (after wheeling this weekend since I know my little Viair gauge isn't overly accurate) to 38psi. The guy said that they are all inbetween 13-14/32s currently and after looking at the Falken website it seems these come in at 19-20/32nds. So with that being said, do you think that is too large a gap to throw a fifth in the mix?
 

80t0ylc

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Ok so I went and had them measured and inflated (after wheeling this weekend since I know my little Viair gauge isn't overly accurate) to 38psi. The guy said that they are all inbetween 13-14/32s currently and after looking at the Falken website it seems these come in at 19-20/32nds. So with that being said, do you think that is too large a gap to throw a fifth in the mix?
My main concern would be if the 100 series has a VC (viscous coupler). The FZJ80's had a VC in the transfer case and it was sensitive to just what we're talking about. It would heat up and seize eventually since it would be constantly slipping with uneven tires. Most owners would then just pull the VC out and not replace it. The VC acts like a slip limiter between front and rear axles and enhances traction on slippery roads. Not a real game changer until it seizes and then it is like the CDL is permanently locked. And we all know running locked on pavement is not the best for your drive train, tires and nerves. If 100's don't have a VC, you could probably get away with it.
 

e9999

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greg, it's the relative difference in diameter that matters ultimately, not just in tread depth. The former won't be much for a biggish tire. As I said, I think you would be fine if unlocked and it will get better with time if you rotate accordingly. (My hazy recollection is that the 100 does not have a VC - check.) Now of course if you'll have kids or somebody randomly pushing in the CDL switch on asphalt, that would not be so great then (if that switch activates in High - check).
 

80t0ylc

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greg, it's the relative difference in diameter that matters ultimately, not just in tread depth........
Good point, which translates the 3/16" in tread depth difference to 3/8" difference in diameter. That's significant for any tire we run, IMHO. The differential on the axle that the larger tire is on should absorb this, but it will run warmer. Be sure that your diff's gear oil levels are "up to snuff".
 

e9999

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what I meant is that if there is 3/16 difference in thread and the tires are 33" or so then the relative difference is 3/8 out of 33" or only about 1% in diameter. So for every 100 turns the wheel on one side makes, the other would do 101. The diff would only see the difference so 1% of whatever rpms the wheels are going at. I doubt this will be an issue (if not locked on sticky ground).
 

gregnash

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greg, it's the relative difference in diameter that matters ultimately, not just in tread depth. The former won't be much for a biggish tire. As I said, I think you would be fine if unlocked and it will get better with time if you rotate accordingly. (My hazy recollection is that the 100 does not have a VC - check.) Now of course if you'll have kids or somebody randomly pushing in the CDL switch on asphalt, that would not be so great then (if that switch activates in High - check).
what I meant is that if there is 3/16 difference in thread and the tires are 33" or so then the relative difference is 3/8 out of 33" or only about 1% in diameter. So for every 100 turns the wheel on one side makes, the other would do 101. The diff would only see the difference so 1% of whatever rpms the wheels are going at. I doubt this will be an issue (if not locked on sticky ground).

So I am overthinking this is what you are saying to me. LOL...
Damn analytical mind is getting the best of me.
 

80t0ylc

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So I am overthinking this is what you are saying to me. LOL...
Damn analytical mind is getting the best of me.
No worries, isn't that what forums are for? Kicking things around. Getting advice, posting new ideas, giving your opinion....etc.... and at what cost? Not much harm in "overthinking" - it's better than underthinking or some might say "living in denial". In the end, it's your decision. Whatever choice you make, things can change in the blink of an eye. Hitting road hazards can ruin tires and change your strategy unexpectedly. It's wise to keep that in mind. :hmm:
 

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