Tire Advice

[77 K20]

With that size tire I would not even waste the money on gear's for half ton stuff , I would jump up to 8 lug before anything. Another thing if you do a lot of freeway driving you need to be careful with low gear's. The pinion get's small with low gear's and it spins faster with low gear's and over heats the gear oil. I have 4.88's in my crew cab with 44's and in the summer going down the hwy. at 70 for say 40 miles it spits out the vent tube a bit and you can't even put your hand on the diff cover. I was told by my gear guy that 4.88's was max for freeway use because I was going to go with 5.13's , glad I did'nt

Have you ever thought about putting on some of the aluminum diff covers that have cooling fins on them? Some of the guys that tow a lot are running them. Some even have a tapped hole for a temperature sensor.

 

[hirschdalechevy]

For sure , I have one in the rear of my 06 , but I don't drive the 77 c.c. much anymore but it's on my list of thing's I need to do to it.

 

[bucket]

For sure , I have one in the rear of my 06 , but I don't drive the 77 c.c. much anymore but it's on my list of thing's I need to do to it.

Your gear guy's reasoning sounds bogus to me. Is he the one that installed those gears?

Gear ratio alone does not determine the speed that the pinion rotates. Tire size has everything to do with it also. 4.88's with tall tires are no different than say 3.73's with stock tires, and you know as well as I do that a stock truck with 3.73's can run down the highway all day long and do it everyday too.

 

[hirschdalechevy]

The pinion becomes smaller in diameter with lower gear's and it spins much faster no matter what tire size you have. Thats why in some rear ends you have to change the carrier or run a thicker ring gear for lower gear's because the pinion becomes smaller and spin's much faster in the oil. I had 4.11's before and the diff would be fairly warm to the touch , now it's much hotter with 4.88's just like my gear guy said it would. Thats why he talked me out of 5.13's , make's total sense to me.

My other square's have 4.11's and I drive them all the time and they dont get hot like my c.c. with 4.88's.

Right now I am going to change the diff. cover to one that holds more oil , thats how hot it get's. And my gear guy is 62 year's old and has been doing gear's 35 year's , (street and race) and I have had tons of axle's set up by him and never a problem , (unless I was doing something stupid). So I totally trust his word and so does everyone else around here.

 

[bucket]

The pinion becomes smaller in diameter with lower gear's and it spins much faster no matter what tire size you have. Thats why in some rear ends you have to change the carrier or run a thicker ring gear for lower gear's because the pinion becomes smaller and spin's much faster in the oil. I had 4.11's before and the diff would be fairly warm to the touch , now it's much hotter with 4.88's just like my gear guy said it would. Thats why he talked me out of 5.13's , make's total sense to me.

My other square's have 4.11's and I drive them all the time and they dont get hot like my c.c. with 4.88's.

Right now I am going to change the diff. cover to one that holds more oil , thats how hot it get's. And my gear guy is 62 year's old and has been doing gear's 35 year's , (street and race) and I have had tons of axle's set up by him and never a problem , (unless I was doing something stupid). So I totally trust his word and so does everyone else around here.

I understand that the pinion is smaller, but that really has nothing at all to do with it. The fact that it is smaller does not make it spin any faster, unless you are comparing stock gears and tires with steep gears and stock tires... but then the engine will be spinning faster along with the pinion. With larger tires, the engine slows down, along with the pinion. If the motor is not spinning faster than stock, neither is the pinion.

 

[hirschdalechevy]

I will stop by his shop and ask him about it , but thats what he told me , anyway my 4.88 rear is way hotter than my 4.11 truck after a hwy run for sure.

 

[bucket]

I will stop by his shop and ask him about it , but thats what he told me , anyway my 4.88 rear is way hotter than my 4.11 truck after a hwy run for sure.

I'd like to know what he says. My truck with 4.56's and 36's doesn't have a heat issue at all, and it cranks down the highway.