I have 35s on my Jeep because I love to do adventure driving. I am frequently asked by people who want to upgrade their tires if they need to change gear ratios when they increase tire sizes.
Whether or not you will need to regear your Jeep to change to 33s or 35s will depend on what gear ratio you already have and the engine size you have.
The following guide is meant to help you understand your gear ratio a little better.
33s Gear Ratio Requirements
There is a lot of confusion on what gear ratio you will have to have in order to run 33s on your Jeep. If you get really particular about the gear ratio the absolute best ratio for efficiency and maximum torque is 4.30.
The 4.30 is ideal except it is not available for your front differentials. That means you are going to have to go with the 4.56.
Do not worry that the 4.56 will create an over-geared situation. Your tires are going to run flawlessly. The gas mileage of your Jeep is going to improve. This taller gearing option is fabulous for people who drive their Jeeps on a daily basis.
35s Gear Ratio Requirements
The 4.56 gear ratio is perfect for most vehicles running 35s. If you have this ratio you should be able to get through the most difficult obstacles with no problems. You should also get fuel efficiency that is acceptable for daily or frequent driving.
Top Reasons to Regear your Jeep
There are several reasons why you should regear your Jeep.
- When you get larger tires the additional weight of the tires plus their diameter and other features will affect how your drivetrain functions. The axles of a vehicle turn the tires on the vehicle. Your axle shafts measure 1” in diameter. If you have 30-inch tires then the axle needs 30 times greater force to be able to turn the wheels. If you regear the vehicle to a shorter gear then the force sent to the axle is increased. That means while you are driving your engine is experiencing less strain.
- If you do a lot of adventure driving, rock-crawling, and off-road terrain driving.
- If you want to get the top speed possible from your vehicle.
- If you want to get the best fuel efficiency from the vehicle.
- If you want to improve the ride quality of the vehicle.
- If you want to increase your towing capacity.
Will Having The Wrong Gear Ratio Harm My Jeep?
Yes, emphatically yes!!! The gear ratio is critical to the performance of the vehicle. Some of the problems you could face are:
- Damages to the gearbox lead to transmission failure. That is expensive to repair.
- The wrong gear ratio can put your engine under undue stress.
- The miles per gallon will be lowered. Your vehicle will use more fuel.
- The speed your vehicle can reach will be altered.
- Your speedometer will not read accurately and this could lead to tickets.
- The incorrect speedometer readings could cause the computer system to not tell the transmission when to shift gears at the right time.
Where To Find The Gear Ratio Your Vehicle Was Given When Manufactured
Your gear ratio is something you need to know if you plan on making any changes to the vehicle’s performance, clearance, or abilities. If you are not sure of the gear ratio you have it is easy to discover the gear ratio that was installed by the manufacturer.
Inside the driver’s door is a sticker that details important facts about the vehicle. The VIN number is a 17 digit code given to just one vehicle. This code can help you identify what parts are needed on the vehicle, and is required by your insurance company because it identifies the vehicle.
Not every manufacturer includes the gear ratio in the VIN number formation but if yours did the gear numbers will be number four through eight. These numbers are referred to as the VDS numbers and they tell you things like the gear ratio and the model, engine size, and body style of the automobile.
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FAQs for 33
What Is The Best Gear Ratio for 33 in Tires?
The best gear ratio, without knowing your engine size, will be 4.56.
Can you put 33s on a stock Jeep?
Yes, 33s can be used on a stock wheel that has not been lifted.
When Should I Regear My Jeep?
When you increase tire size, when you want to improve fuel economy or when you want to increase speed.
FAQ for 35
Do You Need to Regear With 35-Inch Tires Jeep?
More than likely a tire size increase like this will require a gear ratio change.
What Size Gears Should I Run with 35s?
The best gear ratio for 35s will be close to 4.56.
Will I Need to Regear One or Both Axles?
You will need to regear both axles.
Final Thoughts
Gear ratios are critical to vehicle performance and safety. If you want bigger tires or more fuel economy changing the gear ratio may be necessary. If you are uncertain about whether or not you need to change the gear ratio it is always best to speak to a professional vehicle repair professional than to take the chance of driving with the wrong gear ratio.
