Used tire & 4x4 questions

[dpuckett]

I stumbled across a set of 4 newer tires than what was on my truck, I believe Pirelli Desert Dogs, with about 50-60% tread left for $40 a piece. I measured them after I got home, (all 4 went to rear) and noticed that the "new" tires are about 3/4in taller than the old ones, which are nearly bald. Is this just a difference in tread depth, or is it something to be concerned about? I was referring to possible damage to my 4x4 system. Or am I just being a vehicular hypochondriac? I read somewhere that a guy in a Jeep Cherokee had to replace his transmission, tcase, and diffs, because different brands of the same size tire were different actual sizes, thus making his full time 4wd turn at different rates. I only use my 4x4 the five to ten days a year we have snow. (Loveland and Ft Collins are in "dead zones" Cheyenne and Denver get a foot, and we get flurries. )

Daniel Puckett

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Daniel's current truck: 1993 W350 club cab, 5 speed, treadplate aluminum flatbed, 4. 10 rear end, straight pipes, K&N, "slightly" tweaked pump. ISSPRO color coded pyrometer and 50psi boost guage. NRA Life Member (since age 12) and d@mned proud of it. IRBCTS.

[This message has been edited by ddpcfc (edited 02-23-2001). ]

 

[BV]

Running un-equal sized tires on a 4x4 is never a good idea. In the case of the Jeep if very well could have torn everything up if it was full time 4wheel. With your Dodge you could run a little difference (in 4x4 mode) as long as it was NOT on a hard surface. Technically I can't tell you how much is 2 much and don't plan on trying to find out. The fact is, you want to run the front and rear at the same speed otherwise you put things into a bind and something will give out sooner or later.

 

[komual]

Sounds like the difference between d and e load ranges to me...

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1993 W350 Club Cab 5 speed dually. P. W. injectors, Banks stinger, pyro, boost and tach, 22 lbs of boost, and rising... Hey, 'stroke this buddy!

 

[Cooker]

the funny thing is that tires that are of equal size on this sidewall, may actually be a fuz different in size from brand to brand. i have found it not to be uncommon to find things 1/4" - 1/2" difference between mfg's for the same size tire.

I hope you like those tires. i had a set of them that came on the truck when i bought it. i didn't really like them at alll. i guess there a good highway tire but the are terrible, IMO, in the snow. the tire compound is way too hard. i know there E load range and all, but i put on E's and they seem to be a bit softer compound. basically they are good on dry pavement, but heck for only $40 for a decent tire i guess you can't ask for the world huh?

 

[Matt S]

The only time different tire size matters is if you are in 4x4 or have a different size on the same axle with some sort of locking differential. The Jeep was most likely a full-time 4x4. If you only use 4x4 occasionally on a slippery surface then you shouldn't have a problem.

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90 W250, 5-speed, isspro gauges, 16 cm2, K&N, Borgeson shaft, JRE 3" exhaust, Banks Intercooler

 

[dpuckett]

Thanks guys. I had thought along the same lines as you all had mentioned, but just wanted to make sure. As an aside, I did notice they were a little more slippery in the snow, but I also nearly fell on my a$$ a few times, something I dont do in 4" of snow. My roommate noticed it was slicker this time around, too.

Daniel

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Daniel's current truck: 1993 W350 club cab, 5 speed, treadplate aluminum flatbed, 4. 10 rear end, straight pipes, K&N, "slightly" tweaked pump. ISSPRO color coded pyrometer and 50psi boost guage. NRA Life Member (since age 12) and d@mned proud of it. IRBCTS.

 

[Whitmore]

very interesting,I will go one step further,take that tire that was a half inch taller and measure the circumfrunce of it and compare it to the circumrunce of the other tire you would be amazed how different they are! one step further than figure how many revolutions it takes each tire to go one mile and you will be shocked as to the difference. #ad

now I dont have the time to do this but maybe someone does (actually cant count that high).
another bit of trivia,If you have a duelley and you take those two tires we were just talking about and put them on the same side,which one would wear out quicker the taller one or the shorter one?
and the answer to the million doller question is!the shorter one.
you may say hey the taller one would have more weight on it so it would wear out quicker right.
ok the taller tire will turn one revolution with out slipping and the shorter tire will turn one revolution but it had to slip a little bit becasuse its circumfrunce was less!!
please someone tell me I am full of I TRIED TO BY-PASS THE CUSSING FILTER,but this is how I see it #ad
.
Proof of my thinking ,when a duelley pulles in off the highway feel the temp of the duels,if they are the same circumfrance than the temp is the same and if one tire is hotter than measure its circumfrance and I bet the short one #ad
.

. Kevin 2001 eth dee.

 

[dpuckett]

Whitmore,

you bring up a good point. My guess would be the shorter one wearing out, due to the fact is has to turn more revs to go one mile.

The tires match on the same axle, but are different on the front vs back. I have used the 4x4 about 5 times this year, so I am not too worried about drivetrain wear, and someone said it would not hurt, because it is on a slick surface, and thus any discrepencies in D. T. wear would be corrected on the ice or snow.

Daniel

PS- If there is a half difference in height, then there would be about a 1. 5" difference in circumference. Adds up over 5K miles.

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Daniel's current truck: 1993 W350 club cab, 5 speed, treadplate aluminum flatbed, 4. 10 rear end, straight pipes, K&N, "slightly" tweaked pump. ISSPRO color coded pyrometer and 50psi boost guage. NRA Life Member (since age 12) and d@mned proud of it. IRBCTS.

 

[Mel Fuelling]

Another element of this subject to consider:
taller tires on the back of a 4X4 will make it very hard to drive(except for sprint car drivers) because the greater circumference of the tall tires on the rear are trying to pass the shorter(slower)tires on the front.
When you put the tall tires on the front,its
easier to stay out of the ditches, steers much straighter;just keep it out of 4wd unless you're on a greasy surface.

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93 Maroon/Gold D350 CC Dually,5sp,LE trim, A/C,Raven cab height w/contractor side windows, PW inj. , K&N in OEM housing w\altered added inlet, class IV receiver hitch, Maroon cloth 60/40 '97 F150 bench seat, KYB shocks,& behind the seat,not yet installed: Moog upper & lower ball joints, PST poly graphite upper & lower control arm bushings and Praise Dyno Brake pads & shoes.

 

[dpuckett]

Originally posted by Mel Fuelling:
... just keep it out of 4wd unless you're on a greasy surface.

[/B]

I do, I do. Hmmm. Practice for this summer. July? will keep y'all updated.



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Daniel's current truck: 1993 W350 club cab, 5 speed, treadplate aluminum flatbed, 4. 10 rear end, straight pipes, K&N, "slightly" tweaked pump. ISSPRO color coded pyrometer and 50psi boost guage. NRA Life Member (since age 12) and d@mned proud of it. IRBCTS.

 

[Cooker]

Mel,

It seems to me that a shorter tire will be faster, more revs/mile right? And a bigger tire will be slower, less revs/mile?

When you put taller tires on the front it tricks the truck into thinking its a higher gear ratio (numerically lower), so I would rather have the truck pull me more in 4wd with a smaller tire on the front?

Actually I'd rather have the same size tire all the way around and have the trucks gearing take care of things for me. I remember on older GM axles, the front axle had one more tooth than the rear. This was so the truck would pull just a little in 4wd instead of push.

Maybe I've got things all wrong here, but I think that is how I remember it.

Ryan

 

[BV]

Cooker - Try to look at it this way. If you have 2 different height tires side by side and roll then equal times (say 10) which one is going to go farthest from the starting point? The calculator tells me it's the tallest tire since it has the biggest outside diamiter. So if the drive lines are turning at the same RPM then the axle with the tallest tire will try to push or pull it's small brother. This of course can change based on how much traction both tires have.

 

[Cooker]

BV,
I'm overlooking the point that our drivelines, front and rear, HAVE to turn at the same speed.

In theory everyting is nice, the facts are if you had 30" tires on the front and 33" on the back, using 4wd would cause too much harm to the truck. Unless we had a variable drive unit that allowed independent RPM's of each driveshaft, but then the tire issue wouldn't be a problem either.