RE: What is Axle Ratio

[pcasey250]

 
Looking at buying a new tow vehicle and I notice that the axle ratio makes a difference in towing limits. How do you know what the wheel axle ratio is when you look at a car at the dealer or how do you specify what ratio you want?
 Thanks.

[Jeffrey]

 pcasey250
My vans are marked on a sticker on the drivers door frame.
 

[SactoCampers]

 pcasey250
It sounds like you are looking at new cars since you referred to specifying an axle ratio you want.
 
 Therefore, if you re looking at a new car, the axle ratio will be listed on the equipment sticker on the window.
 
 To determine which axle ratio you want (and it s number), refer to that vehicle s brochure or go to kbb.com (Kelley Blue Book) and go to " Optional Equipment."  If there is more than one axle ratio offered, you will find it there. It is often packaged with the towing package.
 
 For used cars, follow Jeffrey s advice, though you will need to know in advance which axle ratio is the one you want. My door jamb of my minivan is relatively useless for this kind of information (no axle ratio, no GCWR). If that fails, take the VIN number and have the dealer run it through their computer.
 
 Finally, make sure you know the vehicle at which you are looking offers more than one axle ratio, if it doesn t, the point is moot.
 
 How do you specify which one you want? You tell your salesman. Make it very clear to them why you want the axle ratio you do and that it is a critical component of your decision. They can be dense, so don t beat around the bush. Be direct.

[birol]

 pcasey250
Usually is a code for the axle ratio  on that sticker, or maybe it was part of the VIN, I forgot ..... Your dealer cann tell you from your VIN what axle ratio the car left the factory with for sure.

[Ab Diver]

 pcasey250
Basically, the *rear* axle ratio is the number of times the driveline turns compared to the number of times the wheel(s) turn one full revolution. The higher the number, the " deeper"  the ratio. In other words, all other things being equal, a truck with a 4.10 rear-end can pull more than a truck with a 3.26 rear-end. The higher number allows the torque of the engine to be multiplied to pull a heavier weight. The flip side is the engine must also turn at a higher RPM to go about it s day-to-day business, and gas mileage suffers accordingly. This is a very simple explanation, and does not take into account engine size, transmission type, and towing options needed to tow whatever it is you have in mind.
 
 Different auto manufacturers have different ways of " listing"  the rear axle ratio, but using the Vehicle Identification Number (VIN) and calling a dealer allows them to tell you how the vehicle was originally equipped, if it s a used vehicle. Buying new, just ask the dealer.
 
 You got a 2001 Bayside, right? What do you want/need to take with you. How big is your family? Is cost and/or fuel mileage a consideration? (dumb question, I know[]) Will you want to tow a larger trailer in a couple years? If buying new, the dealer can help you " dial in"  the right combination for your application. The axle ratio is only one aspect that needs to be looked at when choosing a tow rig.
 
 

[lhuff]

 pcasey250
Axle ratios are only a part of the equation.  The things that are a part of torque/towing power or speed/fuel efficiency are engine, transmission gearing, transfer case gearing, axle (rear end) gearing and tire size.  
 
 An easy example is tire size.  If you have a 4.10 to 1 rear axle  ratio with 27 inch tall tires and change the tires to 30 inch tires, the rear axle ratio will still be 4.10 to 1, but because it takes more torque to pull the taller tires and because the tires will take you farther down the road per revolution, if everything else remains the same, the ratio will seem taller (like maybe 3.73 to 1).  
 
 All of the other stuff listed above has similar effects.  You d need to be an engineer to figure it all out.  The engineers have done the figuring for you and give you the answers in more easily understood terms such as towing capacity, MPG, top speed, etc.  If you re interested in towing your camper, you re better off reading the towing capacity line and leaving axle ratios to that little place in your brain where you store stuff you might one day want to use in conversation (as " yeah man, this new TV has the 5 liter, super torque, gas burner with a heavy duty th400 tranny and positraction 4.10 rear end" ).
 
 Larry

[SactoCampers]

 lhuff

ORIGINAL:  lhuff
 
 Axle ratios are only a part of the equation.  The things that are a part of torque/towing power or speed/fuel efficiency are engine, transmission gearing, transfer case gearing, axle (rear end) gearing and tire size.  
 
 An easy example is tire size.  If you have a 4.10 to 1 rear axle  ratio with 27 inch tall tires and change the tires to 30 inch tires, the rear axle ratio will still be 4.10 to 1, but because it takes more torque to pull the taller tires and because the tires will take you farther down the road per revolution, if everything else remains the same, the ratio will seem taller (like maybe 3.73 to 1).  
 
 All of the other stuff listed above has similar effects.  You d need to be an engineer to figure it all out.  The engineers have done the figuring for you and give you the answers in more easily understood terms such as towing capacity, MPG, top speed, etc.  If you re interested in towing your camper, you re better off reading the towing capacity line and leaving axle ratios to that little place in your brain where you store stuff you might one day want to use in conversation (as " yeah man, this new TV has the 5 liter, super torque, gas burner with a heavy duty th400 tranny and positraction 4.10 rear end" ).
 
 Larry
 

 
 True, Larry, but oftentimes the only difference in tow ratings within a vehicle is the axle ratio. So one must know the axle ratio and code that as an option to get the vehicle you want with the highest towing capacity as well as accurate pricing.(if buying new). All other factors being equal (as they generally are within a model and/or drivetrain), the higher numerical axle ratio, the higher the towing capacity. But you re right, comparing axle ratios outside of a specific model and/or brand will yield very little insight and axle ratio by itself has little meaning in terms of towing capacity.

[pcasey250]

 pcasey250
thanks for the help guys