Here’s the formula for calculating gear ratio: (RPM x Tire Diameter Inches) / (Final Drive Ratio x Transmission Gear Ratio x 336) = Actual numerical gear ratio to the ground from every revolution of the engine.

The gear ratio in a transmission is the ratio between the rotational speeds of two meshing gears. The gear ratio is calculated by dividing the output speed by the input speed (i= Ws/ We) or by dividing the number of teeth of the driving gear by the number of teeth of the driven gear (i= Ze/ Zs).

Gear trains with two gears The “input gear” (also known as drive gear) transmits power to the “output gear” (also known as driven gear). The input gear will typically be connected to a power source, such as a motor or engine.

For example, larger tires decrease your fuel economy because they are heavier, while smaller tires increase fuel efficiency. Bigger tires also have a higher rolling resistance than smaller tires which means they require more resistance and effort to get them rolling.

Divide your old tire diameter by your new tire diameter. Subtract from 1. This will be the % your odometer is off. If your vehicle odometer registers 250 miles and it takes 16 gallons to fill…

Going from 265/70/17 to 275/70/17 isn’t a big deal. Depending on the specific dimensions of the tire, the only difference will be 0.4″ wider and 0.6″ taller per tire. The biggest difference is going to be going from a passenger rated tire to a light truck tire.

Physically fit on a stock rim yes, spec’ed for it no. Stock is 21 x 9–or 20 x 9 for the 20″ group. Widest spec tire on a 9″ wheel in a 35 series is 275.

They both are the same tread width. The difference is the 275/65/17 is a little taller. It is the same tread “mold”. To get a wider bfg tire, you must go to a 285.

The larger 285/70R17 tire in the photo above stands over an inch taller and is nearly an inch wider than the 265/70R17 size. The larger 285/70R17 BFGoodrich All-Terrain T/A KO2 tire in the photo stands over an inch taller and is nearly an inch wider in total than the exact same model of tire in size 265/70R17.

Plus Sizes

YES, 285 wide tires are the same as 33” tires although 285 is the tread width in millimeters and 33″ is the tire diameter. 285/75/16 is usually the accepted metric equivalent size for 33’s.

Tire size equivalent chart for 33″, 35″, 37″ or 40″ tires:

There are many different brands and styles that are available if you are looking for 33-inch tires for your vehicle….

• Yokohama Geolandar A/T G015.
• Toyo Tires Open Country AT II.
• BFGoodrich Mud-Terrain T/A KM2.
• Continental Terrain Contact A/T.
• Federal Couragia M/T Mud-Terrain Radial Tire.

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Most IFS vehicles requires a minimum of 2.5 to 3-inch lift with additional trimming of fender liners and body mounts to accommodate a 33” tire. Fitting bigger tires is the single most effective way of improving ground clearance. This is especially important for overcoming obstacles in an off-road situation.

Depending on exact tire, the 305/55r20 can be a true 33×12. 5 whereas the 33×12. 5 can sometimes be smaller than a true 33″ and 12.5″ wide. And with some manufacturers, the standard sizes (33×12.

P-Metric Tire Sizes – P-Metric to Inches Conversion Chart