35´s with 3.21 gears?

[BAILEY1]

35´s with 3.21 gears?

^^ What?

 

[BigDogg795]

^^ What?

In princip you need more power to turn the wheels. Mountains and so when you got more stress on the gearbox (when it is automatic) Wiel it must always switch up and down.

 

[Bigboytoys]

Gotta love google translator

 

[TheSatinPumpkin]

If you are going to run 35's then just wait until you have them on so you can get your own perception if you need to regear or not.

 

[TheSatinPumpkin]

how can i make sure what gear ratio my truck has? unfortunately there is no sticker or something linke that in my glovebox. and as far as i could see there is no tag on the differential, too. i dont wanna believe that it is only 3.21

Request your build sheet.
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Then click on "I need CUSTOMER ASSISTANCE."

 

[TEXAS]

If you are going to run 35's then just wait until you have them on so you can get your own perception if you need to regear or not.

would this really work? i thought running 35s would stress the gearbox etc that much that the bigger wheels might damage the truck this way?!
if it is not like this i might give it a try - at least this would be an option if the 33`s don´t look that good

 

[TRCM]

silly question...could u explain why? sorry, i am lawyer - not at least cause my physics were not the best in class

is it only due to the higher front in the wind?

Because the frontal area will increase since more of the suspension will be out from under the body, and this will cause more drag when driving it because the airflow that would normally go UNDER the suspension, now has to go THRU it.

Think of it this way....when driving down the road, put your hand straight out the window with the palm horizontal......now turn it vertical. There is a big difference in how much force you need to exert to hold your hand in the same position, right ?

Well, the change in force needed there is similar to the change in force needed to be produced to push your truck thru the air when you lift it up compared to stock. And if more force is needed, then more gas will be used, and thus, mpg will drop.






And as to gears, you could just run the 35's and then make up your mind, but the likely result will be you will lose about 5% of your power and mpg.

And it isn't just the tire height that you need to know, it is the rolling radius. The rolling radius is the height from the axle centerline to the ground, and it takes into account the weight of the vehicle. And on ANY tire out there, when properly inflated, the rolling radius will be lower than 1/2 of the advertised tire height.

As an example, I had 40" tires on my old ramcharger, which would be a 20" dimension to the axle centerline, right ? Well, the rolling radius (with the trucks weight on the tire) was actually 18.5". This is the dimension you should use when calculating how far you go per tire revolution, if you want to do the math.

What I am saying, is a 35" tire, mounted and installed on the truck will in all likelihood only be 33.5" tall when the trucks weight is on it. It will also roll ~8.75' in 1 revolution, whereas if you just use the advertised tire size instead, it will yield ~9.15' per revolution, which would be wrong. These things make a difference when you are trying to correct your speedo, or when trying to figure out how far it is off (not as important in this day of GPS tho, as it was in my younger days).

 

[TEXAS]

Because the frontal area will increase since more of the suspension will be out from under the body, and this will cause more drag when driving it because the airflow that would normally go UNDER the suspension, now has to go THRU it.

Think of it this way....when driving down the road, put your hand straight out the window with the palm horizontal......now turn it vertical. There is a big difference in how much force you need to exert to hold your hand in the same position, right ?

Well, the change in force needed there is similar to the change in force needed to be produced to push your truck thru the air when you lift it up compared to stock. And if more force is needed, then more gas will be used, and thus, mpg will drop.






And as to gears, you could just run the 35's and then make up your mind, but the likely result will be you will lose about 5% of your power and mpg.

And it isn't just the tire height that you need to know, it is the rolling radius. The rolling radius is the height from the axle centerline to the ground, and it takes into account the weight of the vehicle. And on ANY tire out there, when properly inflated, the rolling radius will be lower than 1/2 of the advertised tire height.

As an example, I had 40" tires on my old ramcharger, which would be a 20" dimension to the axle centerline, right ? Well, the rolling radius (with the trucks weight on the tire) was actually 18.5". This is the dimension you should use when calculating how far you go per tire revolution, if you want to do the math.

What I am saying, is a 35" tire, mounted and installed on the truck will in all likelihood only be 33.5" tall when the trucks weight is on it. It will also roll ~8.75' in 1 revolution, whereas if you just use the advertised tire size instead, it will yield ~9.15' per revolution, which would be wrong. These things make a difference when you are trying to correct your speedo, or when trying to figure out how far it is off (not as important in this day of GPS tho, as it was in my younger days).

TRCM, thanks a lot for your explaination. do i got it right: the 35s will only lead to a lower mpg and a little less power? it won´t damage any parts of the gearbox, diff etc - compared to a 3.55-gear ratio?

the last one is my main concern. gearing up is pretty expensive. there are people out the with 3.55-gear ratios and 35s - without any problem. i would like to know if the higher gear ratio (3.21) is that much difference, that it won´t be possible to drive 35s without crashing any parts or so.