Do you want to change your tire size but don’t want to have to buy new rims? Luckily, as long as you stay within specific parameters, you can usually change tire size without having to get new rims.
You can change tire size on the same rim, provided your new tire size falls within the manufacturer’s recommended parameters. If the internal diameter of the tire must match the rim’s diameter, you can usually make the switch without having to purchase new rims.
This article will cover what you need to know about changing the tire size on the same rim, its advantages and disadvantages, and how to read a tire size.
Benefits of Bigger Tires
There are many reasons people might want to change to a bigger tire size while keeping the same rims. The most common reason is to increase ground clearance or improve the vehicle’s look.
Many people believe that a vehicle looks better with bigger tires. While this is strictly a matter of opinion, there are some practical benefits to having bigger tires.
Another reason people might want to change to bigger tires is to increase the tire’s width. This can give the vehicle a more aggressive look.
However, it’s important to note that changing tire size may also change the speedometer reading and cause the vehicle to be less fuel-efficient.
One of the most popular reasons for wanting to change to a bigger tire size on the same rim is to increase the vehicle’s ground clearance. This can be beneficial if you frequently drive on rough roads or off-road.
40-inch tires have become increasingly popular on trucks in the off-roading community to be able to drive over obstacles that would otherwise be impossible.
While larger tires will undoubtedly increase ground clearance, it’s essential to know that they may also decrease the vehicle’s ability to handle correctly.
Greater Off-Road Performance
Another reason people might want to change to bigger tires is for improved off-road performance. Bigger tires can give a vehicle more traction in mud and sand, and they can also make it easier to drive over obstacles.
By increasing the tire’s aspect ratio or sidewall length, the truck has more sidewall to grip on large obstacles like rocks.
Disadvantages of Bigger Tires
While there are some advantages to changing to a bigger tire size on the same rim, there are also some disadvantages that you should be aware of.
Worse Car Handling
One of the biggest disadvantages of changing to a bigger tire size on the same rim is that it can negatively affect the vehicle’s handling. This is because the larger tires will have more rolling resistance and will also be heavier.
This can make the vehicle harder to turn and can also cause it to brake less effectively.
Additionally, increasing the car’s clearance increases its center of gravity, making it more prone to rollover accidents.
If you frequently drive in inclement weather, changing to a bigger tire size may also make it more challenging to maintain control of the vehicle. The risk of hydroplaning increases with wider tires.
Bigger Wheels = Bigger Bills
Another disadvantage of changing to a bigger tire size is that it will generally cost more money. Not only do bigger tires cost more, but you will also need to purchase new rims if your current ones are unable to accommodate the larger tires.
Furthermore, bigger tires will generally wear out more quickly than smaller ones requiring more frequent replacement.
Lower Fuel Economy
One of the most significant disadvantages of changing to a bigger tire size is that it will usually result in a lower fuel economy. This is because the larger tires will have more rolling resistance, which will cause the vehicle to use more fuel.
If you’re looking to save money on gas, it’s generally best to stick with the stock tire size.
Increased Road Noise
Another downside of bigger tires is that they generally create more road noise than smaller tires. This is because the larger contact patch of the tire will cause it to grip the road more, which will generate more noise.
If you’re looking for a quiet ride, changing to a bigger tire size is probably not the best idea.
Speedometer Reading Incorrect
Another disadvantage of changing tire size on same rim is that it can cause the speedometer reading to be inaccurate. This is because the new tires will have a different circumference than the old ones.
This can cause the speedometer to over- or underestimate your actual speed, which can be dangerous.
Changing to a bigger tire may void your warranty if you have a newer vehicle. This is because most manufacturers design their cars to be used with a certain tire size.
Changing to a different size may void certain aspects of the warranty, such as the powertrain warranty.
Reading Tire Size
When looking at tire sizes, you’ll notice a series of numbers listed on the side. These numbers indicate the tire’s width, aspect ratio, and diameter.
For example, a tire size of P225/75R15 would indicate it’s a tire for a passenger car (P), a width of 225mm, an aspect ratio of 75%, and a diameter of 15 inches.
To figure out what size tires you need, you’ll first need to know your current tires’ width, aspect ratio, and diameter. You can find this information on the sidewall of the tire.
Once you have this information, you can use it to find tires that will fit your vehicle.
Metric Tire Size
P, LT, T, and ST, are commonly used terms that you’ll see on tires’ sidewalls. Here’s what they mean:
P-Metric: These are passenger car tires designed to meet the average driver’s needs.
LT-Metric: These are light truck tires designed for use on vehicles such as SUVs and pickup trucks.
T-Metric: These are temporary spare tires not meant for extended use.
ST-Metric: These are special trailer tires designed for use on trailers.
The width of a tire is the measurement from one sidewall to the other in millimeters. For our example, the width is 225 millimeters sidewall to sidewall.
The aspect ratio is the height of the tire’s sidewall as a percentage of the width. In our example, the sidewall is 75% as tall as it is wide.
There are two tire construction types: diagonal (bias) and radial. Diagonal tires have layers of cord that run diagonally from one bead to the other. Radial tires have layers of cord that run perpendicular to the bead.
Most passenger car tires are radial tires.
The rim diameter is the measurement of the wheel’s opening in inches. In our example, the rim diameter is 15 inches.
A load index is a number that corresponds to the maximum amount of weight the tire can support. The higher the number, the greater the weight capacity.
You can read more about a tires load index on Tires Plus.
The speed rating is the last letter, and it corresponds to the maximum speed the tire can travel. All tires are not designed to go 120 mph.
For example, a P-metric tire with an “S” speed rating has a maximum speed of 112 mph.
A “T” rated tire has a maximum speed of 118 mph.
An “H” rated tire has a maximum speed of 130 mph.
And finally, a “V” rated tire has a maximum speed of 149 mph.
The higher the letter, the higher the speed.
Before Changing Tires
Before changing tire size on same rim, you need to consider a few key aspects.
The Tire’s Diameter Must Match the Rim
One of the most important aspects of selecting a new tire size is ensuring that the tire’s diameter matches the rim diameter. If the two dimensions are different, the tire will not be able to fit on the rim.
The Tire Must Fit the Wheel Well
Another essential aspect to consider is whether or not the tire will fit in the wheel well. Some tires are too big and will not fit without rubbing on the suspension or body.
It’s generally best to stick with a tire size that’s been designed for your vehicle to avoid any fitment issues.
Essentially, you need to make sure that the new size will fit on your vehicle without rubbing.
Tire Sizes for Different Vehicles
There are a few different ways to figure out what size tires you need. You can use the tire size that came with your vehicle or consult your owner’s manual.
If you’re not sure what size tires to get, it’s always best to consult your owner’s manual. The manufacturer knows what size tire is best for the vehicle and will list it there.
After the Tire Change
Once you’ve changed to bigger tire sizes, there are a few things you need to do to ensure that your vehicle is safe and functioning correctly.
Balancing the Wheel
It’s essential to balance the wheel after changing tire sizes. This is because the larger tires will throw off the balance of the wheel, which can cause vibration and make the ride less comfortable.
It’s generally best to have a professional balance the wheel after changing tire sizes.
Recalibrate the Tire Pressure Monitoring System
If your vehicle is equipped with a TPMS, it will need to be recalibrated after changing tire sizes. This is because the system is designed to work with a certain tire size and will not be accurate if the size is changed.
Recalibrate the Vehicle’s Speedometer
As mentioned earlier, changing tire size can cause the speedometer reading to be inaccurate. For this reason, it’s essential to recalibrate the speedometer after changing tire sizes.
This can usually be done by taking the vehicle to a local dealership or service center.
Changing tire size can be a great way to improve your vehicle’s performance, but it’s essential to do it correctly.
Before changing to a bigger size, make sure that the tire’s diameter matches the rim diameter and that the new size will fit on your vehicle without rubbing.
Additionally, make sure to balance the wheel. Recalibrate the speedometer and TPMS if needed after changing tire sizes.