Discount Tire Tire Size Calculator
Use this calculator to compare your current tire size with a potential new size. Understanding the differences in overall diameter, sidewall height, and speedometer accuracy is crucial when considering a tire change, whether for performance, aesthetics, or practical reasons. This tool helps you visualize the impact of different tire dimensions on your vehicle.
Current Tire Size
e.g., 205 in 205/55R16
e.g., 55 in 205/55R16
e.g., 16 in 205/55R16
New Tire Size
e.g., 225 in 225/45R17
e.g., 45 in 225/45R17
e.g., 17 in 225/45R17
Calculation Results
'; resultsHtml += '';
resultsHtml += '';
resultsHtml += '
';
resultsHtml += '
';
resultsHtml += '| Metric | Current Tire | New Tire | Difference |
|---|---|---|---|
| Tire Size | ' + currentWidth + '/' + currentAspect + 'R' + currentWheel + ' | ' + newWidth + '/' + newAspect + 'R' + newWheel + ' | |
| Sidewall Height | ' + currentSidewallHeight.toFixed(2) + ' inches | ' + newSidewallHeight.toFixed(2) + ' inches | ' + (newSidewallHeight – currentSidewallHeight).toFixed(2) + ' inches |
| Overall Diameter | ' + currentOverallDiameter.toFixed(2) + ' inches | ' + newOverallDiameter.toFixed(2) + ' inches | ' + diameterDifference.toFixed(2) + ' inches |
| Revolutions Per Mile | ' + currentRevsPerMile.toFixed(2) + ' RPM | ' + newRevsPerMile.toFixed(2) + ' RPM | ' + (newRevsPerMile – currentRevsPerMile).toFixed(2) + ' RPM |
';
resultsHtml += '
';
resultDiv.innerHTML = resultsHtml;
}
.tire-size-calculator-container {
font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
background-color: #f9f9f9;
padding: 25px;
border-radius: 10px;
box-shadow: 0 4px 12px rgba(0, 0, 0, 0.1);
max-width: 900px;
margin: 30px auto;
color: #333;
line-height: 1.6;
}
.tire-size-calculator-container h2 {
color: #0056b3;
text-align: center;
margin-bottom: 20px;
font-size: 2em;
}
.tire-size-calculator-container h3 {
color: #0056b3;
margin-top: 25px;
margin-bottom: 15px;
font-size: 1.4em;
border-bottom: 2px solid #eee;
padding-bottom: 5px;
}
.tire-size-calculator-container p {
margin-bottom: 10px;
}
.calculator-inputs {
display: flex;
flex-wrap: wrap;
gap: 20px;
justify-content: center;
margin-bottom: 25px;
}
.input-group {
background-color: #ffffff;
border: 1px solid #e0e0e0;
border-radius: 8px;
padding: 20px;
flex: 1;
min-width: 300px;
box-shadow: 0 2px 5px rgba(0, 0, 0, 0.05);
}
.input-group label {
display: block;
margin-bottom: 8px;
font-weight: bold;
color: #555;
}
.input-group input[type="number"] {
width: calc(100% – 20px);
padding: 10px;
margin-bottom: 5px;
border: 1px solid #ccc;
border-radius: 5px;
font-size: 1em;
}
.input-group .input-hint {
font-size: 0.85em;
color: #777;
margin-top: -5px;
margin-bottom: 15px;
}
.tire-size-calculator-container button {
display: block;
width: auto;
padding: 12px 25px;
margin: 20px auto 30px auto;
background-color: #007bff;
color: white;
border: none;
border-radius: 5px;
font-size: 1.1em;
cursor: pointer;
transition: background-color 0.3s ease;
}
.tire-size-calculator-container button:hover {
background-color: #0056b3;
}
.calculator-results {
background-color: #eaf4ff;
border: 1px solid #cce0ff;
border-radius: 8px;
padding: 20px;
margin-top: 20px;
box-shadow: 0 2px 8px rgba(0, 0, 0, 0.08);
}
.calculator-results h3 {
color: #0056b3;
text-align: center;
margin-bottom: 20px;
font-size: 1.8em;
border-bottom: none;
padding-bottom: 0;
}
.calculator-results h4 {
color: #0056b3;
margin-top: 20px;
margin-bottom: 10px;
font-size: 1.3em;
}
.results-table {
overflow-x: auto;
margin-bottom: 20px;
}
.results-table table {
width: 100%;
border-collapse: collapse;
margin-top: 15px;
}
.results-table th, .results-table td {
border: 1px solid #ddd;
padding: 10px;
text-align: left;
}
.results-table th {
background-color: #e0f0ff;
color: #0056b3;
font-weight: bold;
}
.results-table tr:nth-child(even) {
background-color: #f6faff;
}
.summary-results p {
margin-bottom: 8px;
font-size: 1.1em;
}
.summary-results p strong {
color: #0056b3;
}
.speedo-note, .clearance-note {
font-size: 0.95em;
color: #666;
margin-left: 15px;
border-left: 3px solid #007bff;
padding-left: 10px;
margin-bottom: 15px;
}
.calculator-results .error {
color: #d9534f;
font-weight: bold;
text-align: center;
margin-top: 15px;
}
.article-content {
margin-top: 40px;
padding-top: 20px;
border-top: 1px solid #eee;
}
.article-content h3 {
color: #0056b3;
font-size: 1.6em;
margin-bottom: 15px;
}
.article-content h4 {
color: #0056b3;
font-size: 1.2em;
margin-top: 20px;
margin-bottom: 10px;
}
.article-content ul {
list-style-type: disc;
margin-left: 20px;
margin-bottom: 15px;
}
.article-content li {
margin-bottom: 5px;
}
@media (max-width: 768px) {
.calculator-inputs {
flex-direction: column;
align-items: center;
}
.input-group {
width: 100%;
min-width: unset;
}
.results-table th, .results-table td {
padding: 8px;
font-size: 0.9em;
}
}
Summary of Changes:
'; resultsHtml += 'Speedometer Difference: ' + speedometerDifference.toFixed(2) + '%'; if (speedometerDifference > 0) { resultsHtml += 'Your speedometer will read ' + Math.abs(speedometerDifference).toFixed(2) + '% slower than your actual speed. (e.g., if your speedometer reads 60 MPH, you are actually going ' + (60 * (1 + Math.abs(speedometerDifference / 100))).toFixed(2) + ' MPH)'; } else if (speedometerDifference < 0) { resultsHtml += 'Your speedometer will read ' + Math.abs(speedometerDifference).toFixed(2) + '% faster than your actual speed. (e.g., if your speedometer reads 60 MPH, you are actually going ' + (60 * (1 – Math.abs(speedometerDifference / 100))).toFixed(2) + ' MPH)'; } else { resultsHtml += 'Your speedometer accuracy will remain virtually unchanged.'; } resultsHtml += 'Ground Clearance Change: ' + groundClearanceChange.toFixed(2) + ' inches'; if (groundClearanceChange > 0) { resultsHtml += 'Your vehicle will be raised by ' + groundClearanceChange.toFixed(2) + ' inches.'; } else if (groundClearanceChange < 0) { resultsHtml += 'Your vehicle will be lowered by ' + Math.abs(groundClearanceChange).toFixed(2) + ' inches.'; } else { resultsHtml += 'Your vehicle\'s ground clearance will remain virtually unchanged.'; } resultsHtml += 'Understanding Your Tire Size
Tire sizing can seem like a cryptic code, but it's actually a standardized system that provides crucial information about a tire's dimensions. A common tire size, like 205/55R16, breaks down as follows:
- 205: This is the tire's section width in millimeters. It measures the width of the tire from sidewall to sidewall.
- 55: This is the aspect ratio, expressed as a percentage. It represents the height of the tire's sidewall as a percentage of its width. In this case, the sidewall height is 55% of 205mm.
- R: This indicates the tire's construction type, with 'R' standing for Radial, the most common type today.
- 16: This is the diameter of the wheel (rim) in inches that the tire is designed to fit.
Why Use a Tire Size Calculator?
Changing tire sizes, even slightly, can have a significant impact on your vehicle's performance, safety, and even its legal compliance. Our Discount Tire Tire Size Calculator helps you understand these impacts before you make a purchase.
Impact of Changing Tire Size:
- Speedometer Accuracy: This is one of the most critical considerations. If your new tires have a different overall diameter than your original tires, your speedometer and odometer will no longer be accurate. A larger diameter tire will make your speedometer read slower than your actual speed, while a smaller diameter tire will make it read faster. This can lead to speeding tickets or inaccurate mileage tracking.
- Ground Clearance: A larger overall diameter will raise your vehicle, increasing ground clearance. A smaller diameter will lower it. This affects your vehicle's center of gravity, potentially altering handling characteristics and off-road capability.
- Fender Clearance: Taller or wider tires might rub against your vehicle's fenders, suspension components, or inner wheel wells, especially during turns or when the suspension compresses. This can cause damage to both the tire and the vehicle.
- Ride Comfort: Tires with a higher aspect ratio (taller sidewall) generally offer a more comfortable ride as the sidewall can absorb more road imperfections. Lower aspect ratio tires (shorter sidewall) typically provide a firmer ride but can offer better handling and responsiveness.
- Handling and Performance: Changes in tire width, aspect ratio, and overall diameter can affect steering response, grip, braking performance, and cornering stability. Wider tires often provide more grip, but can also increase rolling resistance.
- Fuel Economy: Larger or wider tires can increase rolling resistance and vehicle weight, potentially leading to a decrease in fuel efficiency.
- Gear Ratio: For vehicles with manual transmissions or specific performance tuning, a significant change in tire diameter can effectively alter the final drive ratio, impacting acceleration and engine RPM at various speeds.
How to Use This Calculator
- Enter Current Tire Size: Find the numbers on your existing tires (e.g., 205/55R16) and input the width (205), aspect ratio (55), and wheel diameter (16) into the "Current Tire Size" fields.
- Enter New Tire Size: Input the dimensions of the tire you are considering into the "New Tire Size" fields.
- Click "Calculate": The calculator will instantly display a comparison of key metrics like sidewall height, overall diameter, revolutions per mile, and the crucial speedometer and ground clearance differences.
Always consult with a tire professional, like those at Discount Tire, before making a final decision on new tire sizes. They can provide expert advice tailored to your specific vehicle and driving needs, ensuring safety and optimal performance.