If you’ve ever upgraded your vehicle with larger wheels, you’ve probably heard terms like Plus One or Plus Two sizing. Plus sizing is one of the most common modifications among car enthusiasts because it improves appearance and can enhance handling without dramatically changing the vehicle’s overall tire diameter.
However, plus sizing isn’t simply about installing bigger wheels. To maintain proper performance, you must also select the correct tire size. Choosing the wrong combination can lead to inaccurate speedometer readings, reduced ride comfort, suspension rubbing, or premature tire wear.
This guide explains what plus sizing means, the different types of plus sizing, how it works, its advantages and disadvantages, and how to choose the right combination for your vehicle.
What Is Plus Sizing?
Plus sizing is the process of increasing your vehicle’s wheel diameter while reducing the tire’s sidewall height to keep the overall tire diameter as close as possible to the factory specification.
The goal is simple:
- Install larger wheels.
- Use lower-profile tires.
- Maintain nearly the same overall tire diameter.
Keeping the diameter similar helps minimize changes to:
- Speedometer accuracy
- Odometer readings
- Gear ratios
- Ground clearance
- Electronic stability systems
Why Do Drivers Choose Plus Sizing?
Many drivers choose plus sizing for both appearance and performance.
Common reasons include:
- Better-looking wheels
- Sportier stance
- Improved steering response
- Better cornering stability
- More aftermarket wheel options
- Increased brake caliper clearance on some vehicles
When done correctly, plus sizing allows larger wheels without significantly changing how the vehicle performs.
Understanding Factory Tire Size
Suppose your vehicle comes with:
205/55R16
This means:
- Tire Width: 205 mm
- Aspect Ratio: 55%
- Wheel Diameter: 16 inches
If you install larger wheels, you must reduce the tire sidewall to keep the overall diameter close to the original.
What Is Plus Zero Sizing?
Plus Zero means keeping the same wheel diameter while changing tire width or aspect ratio.
Example:
Factory Tire
205/55R16
Alternative
215/50R16
The wheel remains 16 inches, but the tire dimensions change slightly.
Drivers usually choose Plus Zero sizing when:
- Replacing unavailable tire sizes
- Improving grip
- Finding a lower-cost replacement
- Using seasonal tires
Advantages of Plus Zero
- No new wheels required
- Lower upgrade cost
- Minimal speedometer changes
- Factory ride comfort remains similar
- Easy replacement option
What Is Plus One Sizing?
Plus One means increasing the wheel diameter by one inch while reducing the tire sidewall.
Example:
Factory
205/55R16
Plus One
225/45R17
The wheel increases from 16 to 17 inches, while the tire sidewall becomes shorter.
Overall diameter remains very close to factory specifications.
Benefits of Plus One
- Sharper steering
- Better handling
- Improved appearance
- More wheel choices
- Better cornering stability
Possible Drawbacks
- Slightly firmer ride
- Higher tire replacement cost
- Less protection against potholes
What Is Plus Two Sizing?
Plus Two increases wheel diameter by two inches.
Example
Factory
205/55R16
Plus Two
225/40R18
The larger wheel requires an even shorter sidewall.
Drivers usually notice:
- More responsive steering
- Improved cornering
- More aggressive appearance
However:
- Ride quality becomes firmer.
- Wheels become more vulnerable to pothole damage.
What Is Plus Three Sizing?
Plus Three means increasing wheel diameter by three inches.
Example
Factory
205/55R16
Plus Three
225/35R19
This setup is common on sports cars and premium performance vehicles.
Advantages include:
- Excellent steering response
- Sporty appearance
- Reduced sidewall flex
Possible disadvantages:
- Very firm ride
- Greater wheel damage risk
- Higher tire costs
- Increased road noise
Plus Sizing Comparison
| Type | Wheel Increase | Sidewall | Ride Comfort | Handling |
|---|---|---|---|---|
| Plus Zero | None | Similar | Excellent | Similar |
| Plus One | +1 inch | Slightly shorter | Very Good | Better |
| Plus Two | +2 inches | Lower | Good | Much Better |
| Plus Three | +3 inches | Very Low | Fair | Excellent |
How Plus Sizing Works
The key principle is maintaining nearly the same overall tire diameter.
Instead of increasing both the wheel and tire height, the tire sidewall becomes shorter.
Example
Factory
205/55R16
Approximate Diameter
632 mm
Possible Plus One
225/45R17
Approximate Diameter
634 mm
The difference is very small, helping maintain factory driving characteristics.
Why Maintaining Tire Diameter Matters
Keeping the diameter close to factory specifications helps reduce:
- Speedometer error
- Odometer error
- ABS calibration changes
- Traction control differences
- Transmission shift changes
Many enthusiasts try to keep diameter changes within approximately 3%.
Remember:
The 3% guideline is not a guarantee of proper fitment.
How to Choose the Right Plus Size
Before upgrading, compare:
- Overall diameter
- Tire width
- Sidewall height
- Wheel width
- Wheel offset
- Backspacing
- Load rating
- Speed rating
Using the Tire Size Comparison Calculator on FitmentCalculator.com makes it easy to compare the factory tire with a proposed plus-sized setup before purchasing wheels and tires.
Plus Sizing and Wheel Width
Larger wheels are often wider.
Every tire has an approved rim width range.
Installing an incorrect combination may cause:
- Uneven tread wear
- Poor handling
- Tire bead issues
- Reduced steering stability
Always verify the manufacturer’s approved rim width for your selected tire.
Plus Sizing and Wheel Offset
Changing wheel diameter often involves changing wheel offset.
Incorrect offset may cause:
- Suspension rubbing
- Fender rubbing
- Increased steering effort
- Wheel bearing stress
- Brake clearance issues
Before ordering aftermarket wheels, compare both the tire size and wheel offset.
Fitment depends on much more than tire diameter.
Common Plus Sizing Mistakes
Buying Wheels Before Comparing Tire Sizes
Always compare tire dimensions first.
Ignoring Wheel Offset
Many rubbing problems occur because of incorrect offset rather than tire size.
Choosing Appearance Over Function
Extremely low-profile tires may look attractive but often reduce ride comfort significantly.
Ignoring Load Rating
Replacement tires should meet or exceed the vehicle manufacturer’s recommended load index.
Forgetting Speed Rating
Sportier wheels should never reduce the required speed rating.
Before Installing Larger Wheels
Use this checklist.
| Item | Verify |
|---|---|
| Overall diameter | ✔ |
| Tire width | ✔ |
| Sidewall height | ✔ |
| Wheel width | ✔ |
| Wheel offset | ✔ |
| Bolt pattern | ✔ |
| Center bore | ✔ |
| Brake clearance | ✔ |
| Suspension clearance | ✔ |
| Fender clearance | ✔ |
| Steering lock clearance | ✔ |
| Load index | ✔ |
| Speed rating | ✔ |
Completing these checks helps reduce the risk of fitment issues after installation.
Which Calculator Should You Use?
If you’re planning a plus-size upgrade, start with the Tire Size Comparison Calculator to compare your factory tire against the new size.
After comparing dimensions, use the Speedometer Error Calculator to estimate any change in speedometer accuracy.
If you’re also changing wheels, the Wheel Offset & Backspacing Calculator can help you understand how the new wheel position differs from your factory setup.
Using all three tools together provides a much better understanding of your planned upgrade.
Frequently Asked Questions
Is Plus One sizing better than Plus Two?
For most daily drivers, Plus One provides an excellent balance between appearance, handling, and ride comfort. Plus Two offers sportier handling but generally results in a firmer ride.
Does plus sizing improve handling?
Usually yes. Shorter sidewalls reduce tire flex during cornering, which can improve steering response and stability.
Does plus sizing affect fuel economy?
It can. Larger wheels and wider tires are often heavier and may increase rolling resistance, depending on the tire design.
Can I use larger wheels without changing tire size?
No. Installing a larger wheel with the same tire size usually increases the overall tire diameter significantly, affecting speedometer accuracy and vehicle performance.
Is plus sizing safe?
When the correct tire size, wheel width, wheel offset, load rating, and speed rating are selected, plus sizing can be a safe upgrade. Always verify the complete fitment before installation.
Does plus sizing guarantee better performance?
Not always. Tire compound, tread design, wheel weight, suspension setup, and driving conditions also play major roles in overall vehicle performance.
Final Thoughts
Plus sizing is one of the most popular wheel and tire upgrades because it combines improved appearance with sharper handling. By increasing wheel diameter while reducing tire sidewall height, drivers can maintain a similar overall tire diameter and minimize changes to speedometer accuracy and vehicle dynamics.
However, successful plus sizing requires more than choosing larger wheels. Always compare tire dimensions, verify wheel specifications, and check physical clearances before making any changes. Using the right calculations and following manufacturer recommendations helps ensure your upgraded setup performs safely, looks great, and delivers the driving experience you expect.
Sources
- National Highway Traffic Safety Administration (NHTSA) – Tire replacement and safety guidance.
- U.S. Tire Manufacturers Association (USTMA) – Tire sizing and maintenance recommendations.
- Michelin Technical Resources – Plus sizing and tire fitment information.
- Bridgestone Tire Education Center – Tire dimensions, wheel sizing, and replacement guides.
- Goodyear Tire Learning Center – Tire construction and plus sizing guidance.
- Vehicle owner’s manual and tire information placard for original equipment tire specifications.