# Tire Test - Continental Grand Prix 4000S II Latex Tube

Published: 2014-08-14 | Jarno Bierman

### Test Summary

**Conclusion: **5 / 5 Highly Recommended

**Weight: **215 grams

**Rolling Resistance: **10.6 watts

**Puncture Resistance: **11 / 5

This is a retest of the Continental Grand Prix 4000S II reviewed
**Here** except this time I've substituted the standard 100 grams Continental butyl inner tube for a 80 grams Michelin AirComp A1 Latex tube. I've chosen the GP4000S II to test a latex inner tube simply because it's the fastest road bike tire I had the chance to test up to now. I've also tested the Vittoria Open Corsa CX III with a latex tube, results are **Here**. Why a Michelin latex tube instead of some other brand? Because it's the cheapest and best available latex tube.

**Buy Continental Grand Prix 4000S II Latex Tube at Amazon.com**

If you're purely interested in the differences between butyl and latex tubes, I recommend you to also read this **special article** which includes latex,butyl and light butyl tubes.

Everybody wants "free" speed, latex tubes are faster for sure but have some disadvantages when compared to butyl inner tubes as well. The biggest problem is that latex tubes lose pressure quite quickly. When setting air pressure to 100 psi in the morning, you'll probably only have 90 psi left over in the evening and 80 psi the next day. This means you will have to check air pressure and inflate your tires every day. If you just want to set and forget, stick to standard butyl tubes. The second problem is that you have to be really careful when mounting your tires and make sure your rim does not have any sharp edges as these will rip the latex tube apart.

## Inner Tubes Specifications

### Butyl Inner Tube

**Brand:**Continental**Model:**Race 28, 18-25 x 622**Weight:**100 grams

### Latex Inner Tube

**Brand:**Michelin**Model:**AirComp A1 Latex**Weight:**80 grams

Manufacturer Specifications | |
---|---|

Brand | Continental |

Model | Grand Prix 4000S II Latex Tube |

Year | 2014 |

Tire Type | Tubetype (clincher) |

Supplied By | Bought in store |

New or Used | New |

Mileage | 0 km |

Price Range | High |

Price |
Amazon.com |

Part number | 0100945 |

TPI | 3/330 |

Compound | Black Chili |

Bead | Folding |

ETRTO | 25-622 |

Size Inch | 28" |

Width | 25 |

Specified Weight | 225 grams |

Max Pressure | 120 |

Made In | Germany |

Available Sizes |
20-622 (700x20C) 23-622 (700x23C) 25-622 (700x25C) 28-622 (700x28C) 23-571 (650x23C) |

## Test Results

### Size and Weight Measurements

Size and Weight Measurements (Bike Wheel: 622x17C, Pressure: 100 psi / 6.9 bar) | |
---|---|

Specified Weight | 225 grams |

Measured Weight | 215 grams |

Measured Width | 27 mm |

Measured Height | 25 mm |

Total Tire Thickness Center | 2.9 mm |

Total Tire Thickness Sidewall | 0.55 mm |

No differences, same as with butyl inner tube.

### Rolling Resistance Test Results

Rolling Resistance Test Results (Speed: 29 kmh / 18 mph / 8 m/s, Load: 42.5 kg / 417 N) | |
---|---|

Inner Tube | Michelin Latex |

Rolling Resistance 140 psi / 9.7 Bar |
Not TestedCRR: Not Tested |

Rolling Resistance 120 psi / 8.3 Bar |
10.6
WattsCRR: 0.00318 |

Rolling Resistance 100 PSI / 6.9 Bar |
11.1
WattsCRR: 0.00333 |

Rolling Resistance 80 PSI / 5.5 Bar |
11.8
WattsCRR: 0.00354 |

Rolling Resistance 60 PSI / 4.1 Bar |
13.3
WattsCRR: 0.00399 |

Use the formula: RR (watts) = CRR * speed (m/s) * load (N) to calculate rolling resistance at a given speed and load |

The latex tube definitely has less rolling resistance when compared to the butyl tube, although the difference isn't as big as seen with mountain bike tires **Read my special MTB article.** Tests are run at 18 mph / 29 km/h, which might be a little low for road bikes.

At lower air pressures, the differences start getting bigger but nothing extreme. A breakdown of the differences at different air pressures:

- At 120 psi / 8.3 bar, the latex inner tube has 1.6 watts less rolling resistance.
- At 120 psi / 8.3 bar, Coefficient of rolling resistance (CRR) is 0.00048 lower
- At 100 psi / 6.9 bar, the latex inner tube has 1.8 watts less rolling resistance.
- At 100 psi / 6.9 bar, Coefficient of rolling resistance (CRR) is 0.00054 lower
- At 80 psi / 5.5 bar, the latex inner tube has 1.9 watts less rolling resistance.
- At 80 psi / 5.5 bar, Coefficient of rolling resistance (CRR) is 0.00057 lower
- At 60 psi / 4.1 bar, the latex inner tube has 2.2 watts less rolling resistance.
- At 60 psi / 4.1 bar, Coefficient of rolling resistance (CRR) is 0.00066 lower

### Puncture Resistance Test Results

Puncture Resistance Test Results (higher is better) | |
---|---|

Puncture Resistance Tread | 11 |

Puncture Resistance Sidewall | 5 |

No differences, same as with butyl inner tube.

## Conclusion

If you want pure speed, latex inner tubes are definitely worth the trouble. When making a correction for an average road bike speed of 23 mph / 36 km/h and a tire pressure of 120 psi, a pair of latex inner tubes have 4 watts less rolling resistance. If you like to run lower pressures, you will save close to 5 watts at 80 psi.

If you ride your bike every day, the 4 to 5 watts lower rolling resistance might not be worth the trouble of having to check air pressure and re-inflate your tires every day. If you forget to check air pressure before a ride, rolling resistance might actually be higher because of the lower air pressure.

- For maximizing performance :
**Latex inner tubes** - Set and forget:
**Butyl inner tubes**

**Update after testing the Vittoria Open Corsa CX III with a latex tube:**

The differences between the Continental Grand Prix 4000S II and Vittoria Open Corsa CX III with latex tubes vs butyl tubes are small. The difference of at most 0.4 watts in a 4 part measurement is too small to draw a conclusion. I think you can use these 2 comparisons as a reference of how much you will gain with a latex tube, even if you have tires with very high rolling resistance or very low rolling resistance, the difference should be about 4-5 watts for a pair of tires when going for latex tubes.

**Buy Continental Grand Prix 4000S II Latex Tube at Amazon.com**

**RATING:
5
/ 5
TEST VERDICT: **

**Highly Recommended**