Press release
Premium a Better Long-Term Investment than LowBudget
Hanover, June 2008. User report.
Steinhagen-based WLS Spedition conducted a comparison of Premium tires with lowcost Chinese-made products. The test was prompted by the rising price of diesel, it
being currently unclear when the latter will reach its peak. For haulage companies,
getting on top of the number one cost factor (i.e. the fuel consumption of their fleets)
appears all the more important. A truck’s fuel consumption is determined not only by
the route, the engine and driving style but also by the tires, or more precisely: their
rolling resistance. The question is: when is it worth investing in resistance-optimized
tires, which may be considerably more expensive to buy?
It was this question that faced WLS Spedition in Steinhagen (near Bielefeld). “We decided
some time ago to fit our articulated vehicles with tires from Aeolus. The decisive factor was
the low purchase price – a purely commercial decision without taking into account the
product’s technical features”, explains manager Thomas Leimkuhl. While a name-brand
trailer tire would be priced at around €400, the equivalent from Aeolus costs just €160. The
price initially seems to speak in favor of the cheaper option.
Given the continuous rise in fuel prices, this spring Leimkuhl had to decide which tires to use
– i.e. how much lower the consumption was with rolling-resistance-optimized tires. “We don’t
implicitly trust manufacturer advertising alone”, he explains. Leimkuhl does have faith in the
help of a technically experienced workshop partner, with whom he developed a comparison
test designed to produce the most objective results possible. This involved fitting an
articulated vehicle entirely with Aeolus tires and an equivalent reference combination with
tires from Continental (see “The test vehicles”). Both vehicles were then given the same load
– roller shutters made of aluminum and accessories – with a total weight in each case of 25
tons, and first put through a warm-up drive.
They then traveled from Steinhagen to the Schüttdorfer Kreuz junction – there and back a
total of 208 kilometers, of which around 170 were on autobahns (A30 and A33) and the
remainder on an ordinary road.
General conditions
The vehicle running on Aeolus tires started first, with the other following. Cruise control
ensured a largely uniform speed and prevented the drivers exceeding the 85 km/h limit. A
flow-rate gauge monitored consumption during the journey. The trucks were manned by
professionals who know their Volvo FH inside-out and drove it as fuel-efficiently as possible.
Also on board were the automated I-Shift transmission, which likewise ensured a fuelpreserving trip. After returning, the mechanics swapped the tires, i.e. fitting each set at the
same position on the other vehicle; then the trucks embarked on another test trip – except
that this time the vehicle with Conti tires drove off first.
The result after 416 kilometers
The resistance-optimized Conti tire saved an average of 3% diesel. When fitted with the
Premium models, the vehicles consumed an average of 29.3 liters of diesel for 100
kilometers, while the figure for those with Aeolus tires was 30.4. This constituted an average
difference of 1.1 liters (see “Test results“).
While the difference may not initially sound dramatic, it rapidly adds up when applied to the
WLS fleet comprising 100 articulated vehicles with a mileage of 120,000 kilometers each.
Fitted with Aeolus tires, the WLS trucks would guzzle 132,000 liters of diesel more a year
and therefore, assuming a net diesel price of €1.09, cause additional costs of €143,880. Fuel
prices are soaring, however, and are currently at around €1.20 net; today it would in fact be
€158,400 more. The additional consumption also has consequences for the environment; an
extra 2.9 grams of CO2 were produced per kilometer. Given an annual mileage of 120,000
kilometers, this adds up to an extra 348 kilos per truck – with a fleet of 100 trucks, this
translates into 34.8 tons of additional greenhouse gas emissions.
“Each haulage company has to apply the test for themselves. We adjusted the parameters
precisely to our conditions of use”, argues Leimkuhl. WLS transports primarily high-volume
but at the same time light loads. In many cases, the vehicle’s total weight does not exceed
25 tons. Driving with a total of 40 tons will potentially lead to even higher differences (which
speak in favor of Premium tires); every additional ton of load is connected to increased
consumption. Difficult route profiles likewise affect consumption.
The decision in favor of Premium
Thomas Leimkuhl believes the additional costs for Premium tires rapidly pay off. He is
therefore switching to Continental and accepts the higher acquisition price – again purely due
to commercial considerations, the WLS boss stresses.
At the same time, however, Leimkuhl has not yet had the Aeolus tires removed. He now also
wants to know how high the mileage is of the Chinese imports in order to include this factor
in his calculations – something he had not previously done. He also gives his drivers fuelsaving training sessions, and they are put on the road with a tire-pressure gauge to ensure
that the air pressure is always right and fuel consumption is as low as possible. “Everything
to remain competitive”, says Leimkuhl.
Rolling resistance and fuel consumption
The test vehicles
Tractors
Volvo FH (4x2), 400 hp, Midiliner, automated I-Shift transmission,
Odometer reading: 120,789 km
Volvo FH (4x2), 400 hp, Midiliner, automated I-Shift transmission,
Odometer reading: 109,097 km
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Semi-trailers:
Both from Stern, Steinhagen; 3-axle curtainsiders
Tires
Continental tires
Aeolus tires
Steering axle:
315/70 R 22.5 HSR1
(9 bar)
315/70 R 22.5 HN252
(9 bar)
Drive axle:
295/60 R 22.5 HDR+
(7.8 bar)
295/60 R 22.5 HN 359 (7.8
bar)
Trailer axles:
385/55 R 19.5 HTL
(9 bar)
385/55 R 19.5 HN809
(9 bar)
WLS uses low-profile tires for Midiliners, requiring a side loading height of 2,700 millimeters.
In future, the company intends to fit trailers with 385/65 R 22.5 tires from Continental’s new
HTR2 series. In addition, WLS will be setting the air pressure a little higher than specified by
the manufacturer, as the weight being pulled is often under 25 tons.
Rolling resistance
Rolling resistance evolves through both deformation to tires and the road surface. The
greater the rolling resistance, the more energy needs to be supplied by the engine in order to
propel the truck. The fuel consumption increases. Deformation leads to the tires heating up,
releasing a certain amount of the energy generated by the engine. According to Continental
figures, 10% less rolling resistance translates into 4% less fuel consumption. An average 40ton articulated vehicle driving long-distance thus saves around 1.3 liters of diesel over 100
kilometers. According to Conti, the overall rolling resistance of a trailer-towing truck breaks
down as follows: 15% from the steering axle of the truck, 35% from the drive axle and 55%
from the trailer axles.
Test results
Articulated vehicle with
Continental tires
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Articulated vehicle
with Aeolus tires
Trip 1
Distance
208 km
Average speed
71 km/h
Total consumption
62.4 l
63.3 l
Average consumption
30.0 l/100 km
30.4 l/100 km
Trip 2
Distance
208 km
Average speed
70 km/h
Total consumption
59.5 l
63.3 l
Average consumption
28.6 l/100 km
30.4 l/100 km
Total
Distance
416 km
Total consumption
121.9 l
126.6 l
Average consumption
29.3 l/100 km
30.4 l/100 km
Difference in consumption
- 1.1 l/100 km
+ 1.1 l/100 km
Fleet costs
Average annual mileage per vehicle
120,000 km
Diesel price (net) *
€1.09 /l
Diesel consumption per vehicle per
year
35,160 l
36,480 l
Diesel costs per vehicle (total)
€38,324.40
€39,763.20
Difference in cost per vehicle
- €1,438.80
+ 1,438.80
*Figures current as of April. Source: WLS Spedition
The haulage company
WLS Spedition is based in Steinhagen (Westphalia) and is a specialist in transporting
problem goods. All of its articulated vehicles are therefore fitted with special fastening
devices as well as forklift trucks. Major customers include the food division of the Dr. Oetker
company and Hörmann, a manufacturer of garage and indoor hall doors. The latter’s
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products are transported by WLS right up to the construction site. WLS has been a family-run
enterprise ever since its foundation in 1903 and currently has a workforce of 250. It also
owns an internationally active logistics provider that supports companies in terms of imports,
quality testing and order consignment.
With targeted annual sales of more than €26.4 billion for 2008, the Continental Corporation is one of
the top automotive suppliers worldwide. As a supplier of brake systems, systems and components for
the powertrain and chassis, instrumentation, infotainment solutions, vehicle electronics, tires and
technical elastomers, the corporation contributes towards enhanced driving safety and protection of
the global climate. Continental is also a competent partner in networked automobile communication.
Today, the corporation employs approximately 150,000 people at nearly 200 locations in 36 countries.
The Commercial Vehicle Tires division, which oversees the development, production and global
distribution of truck, bus and industrial tires, posted a turnover of approx. €1.5bn in 2007 with a
workforce of over 8,000 employees.
The tire divisions are an Official Sponsor of FIFA World Cup 2010TM, which will be held in South
Africa. For further details, visit the websites www.ContiSoccerWorld.de, www.ContiFanWorld.com
and www.continental-corporation.com.
Press contact:
Udo Brandes
Head of Press and PR, Commercial Vehicle Tires
Continental AG
Büttnerstrasse 25
30165 Hannover
Germany
Tel.: 0511 938-2923, fax: -2496
e-mail: udo.brandes@conti.de
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