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The Ultimate Wheel and Tire Plus Sizing Guide

Putting the max tire size possible on a car might be aesthetically pleasing, but increasing tire size is not always the best idea. A big tire size difference can cause performance issues for your vehicles. So, where do you stop with plus sizing wheels and tires?

There are different stages of this process and the answer to “What tire sizes are compatible?” greatly depends on your vehicle and driving style. Even if using bigger tires on truck applications is possible, going with lesser tire size substitutions can be a better solution.

Checking the tire specs by size and their compatibility with your car is the first step. Learning more about larger tires and how to check tire compatibility also comes with this.

So, let us teach you how to be a walking, talking oversize tire calculator!

What Is Plus Sizing Tires?

Regarding tires, what exactly is plus-sizing?

Tire size plus sizing is the practice of changing out the original equipment or OE tire size of your vehicle to a larger one. Changing tire size in this manner is also called “inch up” tire sizing. In most cases, this will require the purchase of a new, larger wheel and tire fitment.

But, are tire sizes interchangeable?

The simple answer is no, they are not. Tire compatibility is a tricky question and simply over-sizing a tire is not enough. If you wish to own a car with big tires, increasing the tire aspect ratio won't work.

There are a few rules to follow when adding tire inches to the car's suspension, as it holds the possibility of causing problems. This is why the pros and cons of bigger tires are constantly debated among car modification enthusiasts.

No one can deny that using a taller tire size comes with its benefits, but looking at both sides of the coin is necessary. Therefore, let's see how tire-wheel plus sizing works and whether mounting similar car tire sizes to the OE sizing will work for your driving needs in the ultimate wheel & tire plus sizing guide.

Tire upsizing - tire width differences

How Does Tire Sizing Work?

Plus sizing tires isn't just a simple tire size comparison. There are certain tire conversion aspects drivers need to consider before deciding on bigger tires for truck or car applications.

Using a plus sizing tires calculator is one option. The second is to learn the math behind plus or minus tire sizing, so you will always know which big tire sizes will work for your vehicle.

So, how to choose bigger tires?

It is crucial to carefully go about changing the tire size ratio around, as not all combinations will work for your vehicle. While you might wish to use a wider tire size, it might not fit your existing rims.

Let's take this step by step and go over the entire comparing tire size process, starting with learning more about the tire size itself.

What Do the 3 Numbers Mean on Tire Size?

The three numbers located on the tire's sidewall are the tire size. They represent the tire width, the aspect ratio, and the rim diameter of each tire. While at first glance reading tire dimensions can seem complicated, it is not that hard to master.

In this tire size guide, you can learn which tire measurements are important:

Tire size explained

Do Tire Sizes Have to Be Exact?

While the first two numbers of the tire size can be changed slightly, the rim diameter must be an exact tire match. A small leeway is offered when using wide tire sizes on a specific wheel to plus size a tire. As long as you change the tire width and aspect ratio of tire measurements correctly, the tire will work well on the vehicle.

Still, the difference between wide tires and narrow tires will affect the vehicle's performance.

Do You Have to Increase Tire Pressure When Plus Sizing Wheels?

When it comes to plus size tire pressure, no matter what size tire you have mounted on your car, the recommended psi levels are a good starting point. The important thing is to make sure the different tire size dimensions still can handle the load placed on them.

Alternative tire sizes, where the difference is significant from the OE tires, will need larger psi level changes. But with similar tire sizes, the pressure can be kept at the recommended psi.

How Does Plus Sizing Tires Affect TPMS?

When you compare tire sizes, the TPMS system might not be one of your first thoughts - which is not a big problem. Switching to large tires will not affect the performance of the tire pressure monitoring sensor, as it is tasked with following the changes of psi fluctuations. When changing tire sizes, just make sure to move the TPMS sensors onto the new tires.

How to Calculate Plus Sizing on Tires?

Knowing the allowable tire size difference is the first step. While you might want wide tire sizes on your vehicle, the limits of plus-sizing passenger car tires should not be exceeded. Big tires and wheels need to be carefully chosen, making sure the correct modifications are considered as well, whenever they are needed.

Yes, there is a way to change car tire sizes without using a tire size calculator or a tire size converter - however you wish to call it.

How to Choose Bigger Tires?

The tire plus sizing formula is similar for all tire size conversion options - only lower or higher numbers are used to get to the new car tire size. In other words, whether you want the smallest or biggest tires possible, you will need a similar tire size calculation.

With all of that said, this is your plus sizing guide for tires!

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Tire Comparison Guide

Plus Minus Tire Sizing

Tires downsizing is not that popular, but it can come in handy. It is typically done to improve the performance of plus size winter tires, as by down sizing tires and wheels in such a way improves driving stability on slippery surfaces.

Minus sizing tires includes:

  • With this sizing method you take cars with big tires (relatively big that is) and decrease the rim diameter by 1 inch.
  • Of course, to match the tire size equivalency, the aspect ratio is increased and the tire width is lowered.

Plus Zero Tire Sizing

The plus zero tire sizing calculation is probably the easiest. It uses the same rim diameter as the factory tire size, only changing the tire height and width. Still, keep in mind that with such a tire size diameter, it is possible that bigger rims will be necessary to accommodate the wide tires.

To get the correct plus zero tire size you need to:

  • Increase the tire width and reduce the aspect ratio without changing the wheel size.

Plus One Tire Sizing

With plus 1 tire sizing we are going up a rim size, but buying bigger rims is not enough. The overall tire diameter needs to stay the same. Therefore, upsizing tires in this way results in a wider footprint and a lower sidewall.

Plus 1 sizing tire calculation guide:

  • To keep the same tire circumference when you get rims that are 1" bigger than the OEM tire size boost the tire width by 10 mm while reducing the sidewall height by 10 points.

Plus 2 Tire Sizing

When plus sizing tires includes a two-inch jump from the stock tire size, it is called plus 2 tire sizing. Compared to the tire diameter of the OE size, it is a more drastic wheel and tire size change. But, we will talk about the positive and negative effects of plus 2 sizing tires a bit later.

Tire conversion for plus 2 sizing:

  • The tire size conversion results in a section width that's enlarged by 20mm, an aspect ratio that is reduced by 20 points, and a rim diameter that's larger by 2 inches.

Plus 3 Tire Sizing

Plus 3 sizing is often already considered to be extreme plus tire sizing. This is due to the jump between plus 3 tires and the car's stock tire sizes being 3 inches in the rim diameter.

Get plus 3 sized big tires by:

  • The tire width is increased by 30mm while the height is decreased by 30 points. Additionally, the rim size is also enlarged by 3 inches.

Keep in mind, that doing a tire search by size might not give you the correct tires for alternate tire sizing. Choosing the correct tire size from the numerous tire options can be challenging. But, when switching from stock tire sizes, consulting with a professional about a tire equivalent will be your best bet.

Plus Tire Sizing Guide Examples

Take a look at how the factory tire size (also known as OE tire size) compares to a minus and a plus zero tire size:

car tire size guide for minus and zero plus tire sizing

Tires plus one sizing, plus two sizing, and plus three sizing in contrast to the OEM tire size:

car tire size comparison (plus one, plus two, and plus three sizing)

Pros and Cons of Larger Diameter Tires

Before you decide to change tire sizes and start looking for compatible tires, learning about the pros and cons of mounting bigger tires on trucks is a good idea. Going blindly into a costly process to get equivalent tire sizes in diameter, or even taller tires, might lead to a disappointing outcome.

For this reason, just reading through a tire plus sizes guide is not enough. Reading up on the benefits and downsides of using the largest tire size will save you from the headache.

Benefits of Bigger Tires

Of course, when talking about tire size comparisons, tire plus sizing benefits also become an important topic. Tire size interchangeability, if you wish to have a truck with big tires, will leave you with certain positive outcomes.

So, what are the benefits of plus sizing tires?

Better Clearance for Trucks

When looking at a truck, big tires can lift it up - mainly with the use of leveling kits. This increased distance between the driving surface and the truck's undercarriage improves off-road traction. Correctly following a tire measurement guide will greatly boost the vehicle's performance and traction on various, rugged terrain surfaces.

Enhanced Handling

While mounting wider tires on truck models can ruin their on-road performance (more on that later), the same cannot be said for sports cars. Using an alternate tire size, aka one with a wider footprint, offers better handling at high speeds. However, this is only true if drivers don't mount a leveling kit on the vehicle.

As long as the tire diameters match the OE ones, a bigger tire-wheel fitment will greatly boost controllability, especially cornering and steering responsiveness.

If we increase the sizes of off-road tires, we further increase their off-roading capabilities. This is why the upsized SUVs are popular when the vehicle is mainly for off-road applications.

Style and Aesthetics

The biggest reason why drivers decide to upsize their tires with compatible tire sizes is style. Mounting larger rims with smaller tire sidewalls on sports cars and trucks, without changing the tire's diameter, creates a desirable aesthetic.

Additionally, using a larger tire size, that is still compatible with the vehicle, provides better customizing options. Both sports car and light truck owners will be able to upgrade their rides in any way they desire.

Oversized Tires Problems

The negative effects of plus sizing tires should also be considered. Even if you correctly compare tire size options and find the perfect upsized tire diameter comparisons, you need to be aware of possible negative outcomes.

Here are the cons of plus sizing tires for trucks and cars:

Increased Costs

Bigger tires are more expensive, even if they are good alternatives for your current wheels. When you need to change the rims as well, the costs go even higher.

However, the most costly changes come with installing lifts or leveling kits. This is needed when drivers choose bigger tires that are taller compared to the vehicle's OE tires. Apart from the cost of the larger diameter tires and the wheels, you will need to factor in additional expenses if the overall tire size height is bigger than the original equipment's. This leads to speedometer and odometer adjustments, which is to ensure different tire size heights will not interfere with the vehicle's data that show speed, mileage traveled, and psi changes.

overly big tires on trucks require leveling kits

Decreased Clearance for Cars

While installing a lift on your truck can solve issues related to clearance, when you shop by tire size for your passenger car, the exact opposite can happen. By mounting interchangeable tire sizes on passenger vehicles, the reduced tire sidewall lowers the vehicle's undercarriage, bringing it closer to the ground.

Such a tire upgrade leaves the vehicle vulnerable to damage caused by curbs, potholes, and other road hazards. Comparing tire sizes will also show you the impossible task extremely low-profile, oversized tires face in deep snow and on ice-covered roads. Tire, wheel, and even car damage are more probable.

Ruined Comfort Levels

Change the tire size and experience more discomfort! Sadly, this is another downside of switching to comparable tire sizes. A wider tire conversion size creates more road noise and vibrations. Even if the tire diameter does not change, the width of the footprint will still damage the ride quality. This is especially true for off-road tires. 

Reduced Fuel Economy

Choosing the correct tire size compatibility does not mean wider tires will not ruin the vehicle's fuel economy. Increasing the rim diameter and the tire width, and decreasing the aspect ratio results in a (high) performance tire, in most cases.

However, fuel efficiency is not the strong suit of such tires. Wider footprints create more rolling resistance, which makes the vehicle work harder to maintain its forward motion. Therefore, increasing the tire and wheel size will result in a worsened fuel economy.

Handling Issues

How the new tires compare to the original equipment sizes will determine the vehicle's handling. By mounting the biggest tire size possible, especially when they require the installation of lifts or leveling kits to ensure the tire's safe performance, the car's controllability will be affected.

This is due to large tires creating a higher center of gravity, which leads to the tire's higher body roll and load transfer. While compatible tire sizes can enhance handling, overdoing tire upsizing will result in reduced handling, braking, and cornering capabilities.

Additionally, when compromising the vehicle's height, it is necessary to recalibrate the Advanced Driver Assistance Systems to ensure a adequate performance.

Voided Warranties

Even if the difference in tire sizes is not significant, it can void your vehicle's warranty. This can happen due to different modifications, not just with oversize tires. However, this is a risk car modification enthusiasts are often willing to take.

How Do Bigger Tires Affect Speedometer?

Tire circumferences differ depending on their size. While switching to different tire sizes, following a plus sizing tire chart, will leave you with a similar tire profile, the truth is more complicated.

The tire converter said the tire fit would be good for your vehicle, but there was one thing left out. That is the tire circumference. Big tires and rims have a higher circumference and fewer rotations while the vehicle is in motion. This causes problems for the speedometer and even the odometer.

One of the most important questions you should ask is “Will larger tires affect my speedometer?”, because the answer is often yes.

As a big tire size rotates slower, the speedometer will register a slower speed - which is not the actual speed. The same goes for the odometer, which will count fewer miles during the travel. 

In an ideal world, you can update the car's computer to have the stock tire diameter altered. But, in reality, very few car computer systems allow access to the Electronic Control Module (ECM).

To prevent such issues, the new rim and tire size measurement together should not exceed the diameter of the original tires.

What Happens if Your Tires Are Too Big?

Oversized wheels and tires can cause problems if the actual tire dimensions are larger than the stock tires. Often comparing tires side by side before purchasing them is out of the question, but it is still important to examine tire heights.

The issue is that mounting a larger tire size substitute will lead to clearance and rubbing problems. In other words, choosing incorrect or too-large tire size options will leave the tires rubbing against the vehicle's inner components and body. Furthermore, potential ground clearance issues can arise.

For big tires, extra modifications are needed so they can be used on the vehicle without problems. But even with car modifications, the tire's load durability needs to match or exceed the OE tires.

To prevent such problems, buying the correct tire sizes is crucial. One way to do this is to combine tires online or to consult with a professional when extremely plus sizing a tire.

Frequently Asked Questions

What Size Are My Tires?

You can easily find the answer to "What size tires fit my car?" either on the tires' sidewall or in the vehicle's owner's manual. Typically, cars will also have a sticker on the driver-side door jamb that shows the recommended tire size for your specific car type.

How Much Difference in Tire Size Is Acceptable?

Tire size difference should be considered thoroughly. Generally, it is recommended to stay within 3% of the original equipment tire size's diameter (or height). But, for some vehicles, various modifications can be added to increase this number. Still, overdoing plus sizing is not a good idea.

Will Bigger Tires Lift My Truck?

Yes, generally speaking, bigger tires will lift the car as they increase the ground clearance. This is why they raise the truck's overall height. But, this comes with its negative aspects as well, so carefully consider the downsides before buying bigger tires.

Can You Put Bigger Tires on Stock Rims?

Yes, as long as you check fitment correctly, bigger tires can be mounted on stock rims. As long as the car tire comparison shows that the actual tire size (the tire width, aspect ratio, and rim diameter) of the new tire size works with your stock rims, you can zero plus size tires.