240 gearing


i put 240 tire on my bike wich is a 240 40 18 . according to the gear calculator my tire is 80.3 inches in diameter as compared to 76.9 for the stock tire. my question is i was told that the taller tire messed up my gearing ratio like putting a 36 tooth sprocket on the rear wich will slow my acceleration and hurt top end. can anyone clear this up for me please. also if it did change it what gearing do i need to put it back to stock or as close as possible. thank you


Big: yeah, it DOES throw your final drive off. your acceleration wil DECREASE, but your top end should (theoretically) INCREASE. If stock tire diameter is 76.9, then it has a radius of 38.45, giving you a circumference of approximately 120.8 inches in diameter. The 240 will give you a radius of 40.15, which gives you a circumference of 126.13. What this means is that for every revolution of your back wheel, the bike moves forward 120.8 inches and 126.13 inches, respectively. The bikes speedometer is measuring the revolution of some part (not 100% sure and dont feel like looking because its irrelevant) which is turning in relation to the rear wheel. The bike uses this to calculate speed. If the speedo is BASED on 120.8 inches per revolution of the rear wheel and it is ACTUALLY moving 126.13 inches, then you are going further in one revolution. This will give you a higher top speed, because your final drive ratio has been lowered. Also, your speedometer will not read the same as it did before. You will be going faster, given the same speed reading off the speedo, with the larger diameter tire. Notice I didnt say that your speedo is now off, because they aren't terribly accurate from the factory.

Now, for the acceleration part, and this gets a bit trickier. I'm writing this for you and anyone else reading this, and im making the assumption that SOMEONE reading this didnt take college physics...

Take on faith (notice that "leaving the physics out" part here) that a larger diameter wheel takes more "energy" (the physics thing again) to rotate than a smaller diameter wheel. Also, take on faith that the further out the weight is to the edge of the wheel, the harder an engine has to work to rotate it. What this means for you, rider, is that the acceleration will be slower because more energy is being expended into overcoming the "resistance" of the wheel spinning faster. Also, I'm willing to bet that a 240 wheel and tire weighs a LOT more than the stock wheel does. And all a majority of that weight is at, you guessed it, the OUTSIDE OF THE WHEEL! Heaver wheel means more "resistance" to change of speed as well. honestly, weight is going to play a bigger factor than wheel diameter, but neither of these are working in your favor in going to the 240 wheel and tire combo.

Yeah, that explanation sucks. Try this instead: Put your bike up on stands. Take a little kids bicycle and flip it over. Spin the front tire on your busa. Now, spin the front tire on the kids bike. See which one takes less effort on your part to get spinning quickly. Now, try to stop them with your bare hands. See which one stops easier.

Hope that helps you underststand this a little better.

Now, for the gearing issue: Your overall size has gone up about 4.2 percent. Personally, since our speedos usually are about 5% fast as it is, id leave it alone, and you should still be okay.


thanks ibified that helps me understand that my final gearing has been slowed down and i need to go larger on rear sprocket to get back to stock gearing. do you or anyone know what that gearing would be? thank you


If you want the speedo to be accurate, Id leave the gearing alone, honestly. You're gonna be as close now as you were before you did the wheel change. If you want to be closer to stock gearing, id go up a tooth or two on the back sprocket and you should be close.

This isnt an exact science on these bikes, becaus you're gear ratios are going to be limited by the number of teeth. going up one tooth in the back is gonna change your gearing roughly 2.5% However, it goes back to throwing off your speedo, losing top end, and gaining acceleration again. If you need more detail, PM me and ill get back to you as soon as I can.
Thread starter Similar threads Forum Replies Date
C 240 kit and performance Gen II Busa Information 1
mdpar23 Gen 2 240 Wide Tire Kit Parts and Modifications 4
Slowstang305 Tire pressure PSI with a 240 conversion.... General Bike Related Topics 3
A Texas Mile Rear 240 Recommendations Top Speed 6
B Gen 1 Busa Vs 225 Whp H2 Vs 240 Whp H2 Videos 1
Ham Question For The 240 Wide Guys Busa Mods 6
A 240 Issue General Bike Related Topics 5
edouble88h 240 Help General Bike Related Topics 8
elementnblind Gen 1 240 Kit Help Please General Bike Related Topics 6
edouble88h 240 Drive General Bike Related Topics 0
LeDauz 240 Tire With Turbo ? Turbo 14
B Why Is It That All The 240 Wide Tire Kits Out There Are Off Centered ? Gen II Busa Information 12
L Gen 2 240 wide tire kit questions Busa Mods 1
I Busa 240 rims General Bike Related Topics 2
S 240 kits Appearance mods 18
07busa07 240 kit question General Bike Related Topics 4
B how much to stretch 3-4 inches and 240 tire General Bike Related Topics 8
P 240 swingarm for B-King? B-King General Discussion 7
Chango How many ponies do I loose going to a 240 or 300? General Bike Related Topics 9
turbokaos 240 Single Sided Swingarm Busa Mods 14
InfiniteReality Can I Fit Wider Than A 240??? Tires 17
M What is the width of a 240 swing arm ? Appearance mods 2
Bondo Pics of my Busa and mods: 240, carpeted and 12v trunk, other stuff - Pic whoring..... Gen II Busa Information 32
Bondo Thompson 240 Kit - Chain hits back tire......? Pics.... Busa Mods 38
cer0413 240 kit with 260 tire by FTD customs Busa Mods 5
Z 220/240/360 Tire Mod Busa Mods 21
cer0413 240 kit installation Busa Mods 18
Redliner-Chicago 240/300 tire bike stand General Bike Related Topics 5
H 240 swing arm stand Gen II Busa Information 11
kandy_busa Opinions on shaving frame for center 240 wheel General Bike Related Topics 17
D 240 fat tire kit General Bike Related Topics 7
Stumpybusa Is there a stock length 240 swingarm kit out there? Appearance mods 8
K Best 240 extended swing arm kit?? General Bike Related Topics 14
nabusa cut and welding a stock arm to make it a 240 arm General Bike Related Topics 2
D 240 wide tire kit issues Gen II Busa Information 5
black diamond busa Atlanta area 240 kit Gen II Busa Information 4
R Please help find 240 pics Appearance mods 13
Big Moe 240 Swingarm hardware for install? Appearance mods 5
D 240 vs 300 rear pics Gen II Busa Information 14
coreywiley what do I need to make a complete 240 kit? General Bike Related Topics 5
Busa Brian Frame covers and 240 kit Appearance mods 7
K 240 install General Bike Related Topics 34
K Installing 240 General Bike Related Topics 16
K 240 kit came General Bike Related Topics 17
04LE 240 drag tire Tires 11
J Continental RaceAttack 240 Tires 2
InfiniteReality 240 Widened Rear Wheel + Silver Pinstripes Gen II Busa Information 15
K Nice 240 Kit from Carrozzeria General Bike Related Topics 21
K 240 rear kit General Bike Related Topics 10
T Single side swingarm 240 tire Appearance mods 1
Similar threads

Latest Bikes

  • Bam Bam
    My Last Little Girl
    • rlmoorex
    • Updated:
  • My first Busa - 2012
    Nice, clean and well looked after , my pride
    • Kimbo2570
    • Updated:
  • busa
    nice and clean again first ride since ecu reflash
    • bigjimbo
    • Updated:
  • A blue bike
    2017 blue & black
    • Hayabusa Wannabe
    • Updated:
  • 2011 busa
    2011 limited edition candy sonoma red busa
    • Hetheus
    • Updated:

Forum statistics

Latest member