Top of Second - Second Gear First

Gear ratio calculator with a live RPM vs speed chart.

Build a transmission ratio stack, compare final drive and tire changes, visualize every shift, and answer the autocross question that inspired the site in the first place: how fast are you at the top of second?

Top-of-second speedShift drop analysisPreset transmissions

Autocross-Born Gearing Tools

Quick Read

Current setup snapshot without extra visual clutter.

Live setup

Projected Top Speed

208 MPH

Redline in gear 6

Cruise Snapshot

2688 RPM

Top gear at 70 MPH

Tire Diameter

27.6"

731 revs per mile

6 gears | FD 3.89 | 8,000 RPM redline

Built from the autocross habit of chasing every usable mile per hour at the top of second.

ImperialMetric

Setup Studio

Dial In Your Gear Stack

Shape the transmission, final drive, tire size, and drivetrain assumptions in one place.

Gears

Final Drive

3.89

Redline

8,000

Tire

275/35R20

Transmission Presets

Gear Ratios

1st

2nd

3rd

4th

5th

6th

Rev

Redline RPM8,000

Final Drive (Axle) Ratio

Transmission Type

Transfer Case

Cruising Speed70 MPH

Tire Size

275/35R20 - 27.6 in diameter - 731 rev/mi

Width (mm)

Aspect %

Wheel (in)

Drive

Gear ratios apply to the rear axle. The opposite axle freewheels.

Live Visualizer

RPM vs Speed Map

See each gear's usable sweep, shift landing RPM, and top-speed projection update as you adjust the setup.

FD 3.89 / 6 gears8,000 RPM redline

Swipe for the full chart.208 MPH top speed

Core Output

Ratios, speed, and shift quality

Read top speed, cruise RPM, gear spacing, and landing drops without leaving the page.

Gear Table

Primary speed and RPM reference for each forward gear.

Gear 1

3.310 ratio

Max Speed

51 MPH

Combined

12.876

MPH/1000

6.4

RPM @ 70

10985

Spread Cue

Launch

Gear 2

1.950 ratio

Max Speed

87 MPH

Combined

7.585

MPH/1000

10.8

RPM @ 70

6472

Spread Cue

1 to 2

Gear 3

1.410 ratio

Max Speed

120 MPH

Combined

5.485

MPH/1000

15.0

RPM @ 70

4680

Spread Cue

2 to 3

Gear 4

1.130 ratio

Max Speed

149 MPH

Combined

4.396

MPH/1000

18.7

RPM @ 70

3750

Spread Cue

3 to 4

Gear 5

0.950 ratio

Max Speed

178 MPH

Combined

3.696

MPH/1000

22.2

RPM @ 70

3153

Spread Cue

4 to 5

Gear 6

0.810 ratio

Max Speed

208 MPH

Combined

3.151

MPH/1000

26.0

RPM @ 70

2688

Spread Cue

5 to 6

Gear	Ratio	Combined	MPH/1000	Max Speed	RPM @ 70
1	3.310	12.876	6.4	51 MPH	10985
2	1.950	7.585	10.8	87 MPH	6472
3	1.410	5.485	15.0	120 MPH	4680
4	1.130	4.396	18.7	149 MPH	3750
5	0.950	3.696	22.2	178 MPH	3153
6	0.810	3.151	26.0	208 MPH	2688

Tire: 27.6" diameter (731 rev/mile)Top Speed: 208 MPH in Gear 6

Shift Analysis

Landing RPM and drop quality at each redline shift.

1 -> 2

Shift at redline

Shift Speed

51 MPH

Landing RPM

4713

RPM Drop

3287

Drop %

41.1%

2 -> 3

Shift at redline

Shift Speed

87 MPH

Landing RPM

5785

RPM Drop

2215

Drop %

27.7%

3 -> 4

Shift at redline

Shift Speed

120 MPH

Landing RPM

6411

RPM Drop

1589

Drop %

19.9%

4 -> 5

Shift at redline

Shift Speed

149 MPH

Landing RPM

6726

RPM Drop

1274

Drop %

15.9%

5 -> 6

Shift at redline

Shift Speed

178 MPH

Landing RPM

6821

RPM Drop

1179

Drop %

14.7%

Shift	Shift Speed	Landing RPM	RPM Drop	Drop %
1 -> 2	51 MPH	4713	3287	41.1%
2 -> 3	87 MPH	5785	2215	27.7%
3 -> 4	120 MPH	6411	1589	19.9%
4 -> 5	149 MPH	6726	1274	15.9%
5 -> 6	178 MPH	6821	1179	14.7%

Gear spread: 4.09:1Ratio steps: 1.17 - 1.70

Forum Export

Copy a clean setup summary only when you need it.

Parameter Sweep

Formulas Used

Contextual Placeholder

300 x 100

Performance Parts

performance parts | engine tuning

Workflow Placement

300 x 250

Show up while the build is being decided.

In-feed placement positioned inside active gearing and setup workflows.

Garage Wall Placement

300 x 600

Own the most focused session on the page.

Sticky sidebar inventory designed for long research sessions and high-intent users.

How It Works

Use the calculator like a proper setup board.

Enter your transmission gear ratios, final drive ratio, and tire size to see an interactive RPM vs Speed chart. The chart shows the relationship between engine RPM and vehicle speed for each gear, with shift points at redline and a top speed indicator.

Select from popular transmission presets including Tremec T-56, GM 10L90, ZF 8HP, and many more. Adjust redline RPM, cruising speed, and tire dimensions to see how each change alters gearing feel and highway behavior.

Key Formulas

Speed = RPM x 60 / (Gear Ratio x Final Drive x Revolutions per Mile).Tire Diameter = (Width x Aspect / 100 / 25.4 x 2) + Wheel Diameter.Revolutions per Mile = 63,360 / (pi x Tire Diameter).

Guides

Learn the fundamentals behind the numbers.

Use these quick guides to understand how transmission ratios, final drive, and tire size interact before you start comparing or buying parts.

How to Read Gear Ratios

Understand what the ratios mean, how final drive multiplies them, and how tire size changes effective gearing.

Gear Ratio vs Final Drive

See when to change the transmission, when to change the differential, and when tire diameter is enough.

Common Questions

Quick answers for common gearing decisions.

What does a gear ratio calculator do?

A gear ratio calculator shows how transmission ratios, final drive, tire size, and engine RPM combine to determine vehicle speed in each gear.

How does final drive affect RPM and speed?

A shorter final drive multiplies every gear more aggressively, which improves acceleration but raises RPM at a given speed. A taller final drive does the opposite.

Does tire size change effective gearing?

Yes. A taller tire covers more ground per revolution, which effectively makes the setup taller and lowers engine RPM at the same road speed.

Can I compare two transmissions side by side?

Yes. The comparison tool overlays two RPM vs speed maps so you can see top-speed, cruise RPM, and gear-spacing differences clearly.