2009 Tirerack Ultra low rolling resistance tire test

With petrol prices rocketing and "green" being very much on the agenda, ultra low rolling resistance tires are very much in fashion with the tire manufacturers in 2009. With the hype has come a lot of questions regarding the fuel savings involved, and uncertainty as to whether there's a trade off in grip and performance to achieve the reduction.

Fortunately, the excellent American tire reseller tirerack.com has tested 7 tires ranging from the latest in fuel saving rubber, to the softest "comfort" tires money can buy. There's a link at the end of this page to the full article which we suggest you read, but for now we'll continue the tirereviews tradition and summarise the results.

The car they used was the Toyota Prius. Fitted as stock with the Goodyear Integrity which tirerack used this as the base line for the tests. The Goodyear Integrity was a leading ultra low rolling resistance tire in 2007, but is now comparatively old technology. All the tires were new, and the test route was a 6.6 mile loop for a total of 550 miles on each tire. Instead of relying on the on-board computer for MPG figures, tirerack used a Race Technology DL1 GPS data logger to monitor distance coupled with a Linear-Logic ScanGauge IIs to monitor how much fuel was used! Onto the results.

Tire Line	Test MPG	%
Michelin Energy Saver A/S	53.8	+4.74%
Bridgestone Ecopia EP100	53.5	+4.12%
Yokohama dB Super E-Spec	52.8	+2.81%
Goodyear Assurance Fuel Max	51.6	+0.37%
Goodyear Integrity	51.4	---
Michelin HydroEdge with Green X	51.1	-0.59%
Goodyear Assurance ComforTred	50.0	-2.64%

Surprisingly there is just 4 mpg extra between the best fuel efficient tires compared to the drag heavy "ComforTred". Keeping in mind the test vehicle was the ultra fuel efficient Prius, it's safe to assume you might see a larger percentage saving on a less efficient vehicle. Over the average 15,000 mile year, the difference above (calculated with petrol at ?1.10 / litre) works out to an ?88 saving.

Now the efficiency question is answered, at what cost does that ?88 come in grip? The ever thorough Tirerack took the Prius to the test track to test the cornering and braking ability of each tire in both dry and wet conditions.

Braking (feet)

Tire Line Dry % Goodyear Integrity 96.7 --- Yokohama dB Super E-Spec 97.2 -0.5% Michelin HydroEdge with Green X 97.3 -0.6% Michelin Energy Saver A/S 98.3 -1.6% Goodyear Assurance Fuel Max 99.1 -2.5% Bridgestone Ecopia EP100 101.2 -4.5% Goodyear Assurance ComforTred 101.2 -4.6%

Tire Line Wet % Bridgestone Ecopia EP100 105.2 +20.2% Goodyear Assurance ComforTred 106.7 +19.0% Michelin Energy Saver A/S 107.2 +18.7% Yokohama dB Super E-Spec 107.6 +18.4% Goodyear Assurance Fuel Max 108.7 +17.5% Michelin HydroEdge with Green X 112.5 +14.6% Goodyear Integrity 131.8 ---

Cornering (g-force)

Tire Line Dry % Goodyear Integrity 0.804 --- Yokohama dB Super E-Spec 0.798 -0.7% Michelin Energy Saver A/S 0.795 -1.1% Michelin HydroEdge with Green X 0.795 -1.1% Goodyear Assurance Fuel Max 0.775 -3.6% Bridgestone Ecopia EP100 0.769 -4.4% Goodyear Assurance ComforTred 0.743 -7.6%

Tire Line Wet % Michelin HydroEdge with Green X 0.677 +12.6% Yokohama dB Super E-Spec 0.670 +11.5% Bridgestone Ecopia EP100 0.661 +10.0% Goodyear Assurance Fuel Max 0.653 +8.7% Goodyear Assurance ComforTred 0.641 +6.7% Michelin Energy Saver A/S 0.638 +6.2% Goodyear Integrity 0.601 ---

Unsurprisingly the dry weather results were all fairly close, but the stark contrast between the best and the worst tire in the wet is a testament to how far the new breed of ultra low rolling resistance tires have come in 2009.

Are ultra low rolling resistance tires ready for mass adoption? It's safe to assume any "normal" sports tire would have excelled in the performance tests compared to the ComforTreds average result, and with the ComforTreds double layer of rubber, a normal UHP tire would have closed the gap in fuel economy too making the petrol saving over a year even smaller.

Tirereviews has always been about tire education, allowing you to pick the best tire for your own needs. On that basis, we will leave you to answer the above question. Any comments or questions, please feel free to make them below.

If you're after more data, we strongly suggest reading the full article at tirerack.com! comments powered by Disqus