Question 1

How do I calculate tire speed from RPM?

Accepted Answer

Tire speed is calculated using engine RPM, gear ratios, final drive ratio, and tire circumference. The formula is: Speed = (Engine RPM ÷ (Gear Ratio × Final Drive Ratio)) × Tire Circumference × 60 ÷ 1000.

Question 2

How does the tire size comparison feature work?

Accepted Answer

Our tire comparison tool allows you to compare two different tire sizes side-by-side. Simply select tire types (standard metric or slick inches) for both tires and input their dimensions. The calculator will show you the exact differences in diameter, width, and sidewall height in millimeters.

Question 3

What's the difference between standard and slick tire sizing?

Accepted Answer

Standard tires use metric sizing (e.g., 215/65R15) where the first number is width in mm, second is aspect ratio as percentage, and last is rim diameter in inches. Slick tires use imperial sizing (e.g., 26.0-8.5-15) showing overall diameter, width, and rim diameter all in inches.

Question 4

What are Finnish Racegears?

Accepted Answer

Finnish Racegears are high-performance racing transmission components manufactured in Finland, specifically designed for VW Type 1 transaxles used in drag racing applications.

Question 5

Can I use this calculator for slick tires?

Accepted Answer

Yes, our calculator supports both standard metric tires and American slick tire sizing. Simply select 'Slick (inches)' from the tire type dropdown and choose from our comprehensive list of racing tire sizes.

Question 6

Why would I need to compare tire sizes?

Accepted Answer

Tire size comparisons are valuable when upgrading wheels, changing from street to race tires, or optimizing performance. Different tire sizes affect speedometer accuracy, ground clearance, gear ratios, and overall vehicle dynamics.

Question 7

What are reduction gear options for transaxles?

Accepted Answer

Reduction gear options allow you to select different gear ratios for your transaxle or gearbox setup. These options help optimize performance by changing the final drive ratio, affecting acceleration, top speed, and engine RPM at cruising speeds. Popular ratios include 3.88, 4.12, 4.37, and others depending on your application.

Question 8

How do I choose the right reduction gear for my setup?

Accepted Answer

Choosing the right reduction gear depends on your intended use, engine power characteristics, tire size, and desired performance balance. Lower ratios (numerically higher like 4.37) provide better acceleration but lower top speed, while higher ratios (like 3.88) allow higher top speeds but slower acceleration. Use our calculator to compare different ratios with your specific setup.

VW Transaxle Speed & Gear Ratio Calculator

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