Tyre-Road Noise of New and Retreaded Truck Tyres
Dr.-Ing. Klaus-Peter Glaeser
Federal Highway Research Institute (BASt)
Presenter
Dr.-Ing. Klaus-Peter Glaeser
Federal Highway Research Institute (BASt), Germany
++49 2204 43 630
glaeser@bast.de
Abstract
The measurement of tyre noise emissions is part of the Regulation 2001/43/EC and part
of the ECE Regulation 117; the latter came into force in the year 2005. For truck tyres
(and passenger car tyres as well) the tyre noise test is carried out as a pass by test with a
(loaded) truck equipped with 4 equal (test) tyres with a velocity between 60 km/h and 80
km/h. The measured noise values have to be calculated back to a velocity of 70 km/h and
this calculated value is reduced by one dB(A) (measuring uncertainties) and must be
lower than a limit value which is different for different tyre types.
About half of the trucks in Germany are equipped with retreaded tyres, mainly on the
drive and towed axles. Retreaded tyres are not part of the regulations mentioned above.
One aim of the investigation was to look if retreaded HGV tyres should be incorporated
into the regulation.
In connection with the German retreaders organisation (BRV) two retreading
companies provided BASt with HGV tyres:
• Ihle: 24 sets (18 sets hot retreaded and 6 sets cold retreaded) of HGV tyres (IHL)
• Bandag: 10 sets of cold retreaded HGV tyres(BAN)
• Reference: 5 sets of comparable new HGV tyres
The tyres were built on carcasses of different manufacturers with different profiles for
the different axle positions (steering-, drive- and towed axles). The test truck was a
IVECO Stralis tractor with additional load on the fifth wheel. The test track was the
testing ground of BASt in Sperenberg (surface according ISO 10844). The tests were
carried out by Müller BBM in order of BASt.
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•
•
•
•
•
•
•
All tyres fulfilled the requirements of the Regulation 2001/43EC.
Tyre noise emissions are very different for the different profiles.
Tyres with the same profile but different carcasses used before retreading had nearly
the same tyre noise emissions.
The differences of tyres for the same purpose (axle position) of different
manufacturers with different profile designs vary 2-3 dB(A).
Retreaded tyres were not louder but sometimes more silent than comparable new
tyres.
The noise emission values of all (retreaded and new) test tyres fell far below the limit
values of the Regulation 2001/43EC, e.g. tyres with steering axle profile minus 3 to
minus 6 dB(A).
Compared to 70km/h the tyre road noise is about +2 dB(A) louder at 80 km/h.
No difference was found between cold and hot retreaded tyres.
Tyre-Road Noise of New and Retreaded Truck Tyres
Dr.-Ing. Klaus-Peter Glaeser
Federal Highway Research Institute (BASt)
1. Introduction
In Europe about 45% of all goods are transported on roads. In Germany about 360 Bill. tkm
cargo is transported by trucks (70%) and the annual increase amounts to about 2,5% per year.
About 70% is transported via the federal trunk road network. The share of Heavy Good
Vehicles (HGV) > 3,5 t on motorways amounts to 15% in average, but can reach on some
motorways up to 25 % [1]. Truck traffic is taking place day and night and is annoying for the
population living beside motorways during night (sleeping) time. The noise emission of a
truck moving at 80 km/h is about 3 dB(A) louder than a passenger car moving at 120 km/h.
Figure 1 shows as example the traffic on one measuring site at the motorway A8 vs. time of
day and figure 2 shows the calculated noise emissions from that traffic at a 25 m distance. The
noise of trucks is dominant between 2 and 6 o clock in the night.
4000
HGV
Cars
Time+Light
of DayTrucks
All vehicles
italahrzeuge
No. of vehicles per hour
Motorway A8 Leipheim
3000
2000
1000
0
0
6
12
Time of Day
Fig.1: Motorway Traffic vs. Time of Day
18
24
Total Noise
Cars and Light Trucks
HGV
Traffic Noise in 25m Distance [dB(A)]
70
60
Leipheim A 8
50
0
6
12
18
24
Time of Day
Fig.2: Calculated Traffic Noise in 25 m Distance vs. Time of Day
This was the reason to initiate research work on truck tyre noise emissions. Because half of
the trucks in Germany are equipped with retreaded tyres the study includes new and retreaded
tyres.
Truck-trailer combinations and tractor–semtrailer combinations as well have different tyre
sizes and profiles for the different axles. The tyres can be distinguished in tyres for steering
axles, tyres for drive axles and tyres for towed axles. Steering axle and the wider towed axle
tyres have in most cases a longitudinal profile; drive axle tyres have rib profiles for traction
purposes. Drive axle tyres are in general 3-5 dB(A) louder than the other tyres. This can be
heard if a truck passes by. Figure 3 shows as example a coast-by test with a truck at 80 km/h
and a standard microphone position of 7,5 m from the centreline of the truck. The first peak
shows the noise of the steering axle tyres passing the microphone, the second peak after
0,16 sec is the drive axle tyre noise (same tyre type used in the test).
0,16
Fig. 3: Coast-By Noise Measurement of a Truck at 80 km/h
2. Measuring Program
In connection with the German retreaders organisation two retreading companies provided
BASt with HGV tyres:
•
•
•
24 sets (18 sets hot retreaded and 6 sets cold retreaded1) of HGV tyres (Ihle)
10 sets of cold retreaded HGV tyres (Bandag)
5 sets of comparable new HGV tyres as reference
The tyres were built on carcasses of different manufacturers with the different profiles for the
different axle positions (steering-, drive- and towed axles). The test truck was a IVECO
Stralis tractor with an additional load on the fifth wheel to ensure the required axle load
distribution of 14% for the steering axle and 86% for the drive axle, see Fig 4. The axle
distance was 3,6m (required: <5m). The test track was an ISO surface (according ISO 10844)
laid at the testing ground of BASt in Sperenberg. The tests were carried out according
regulation 2001/43EC by Müller BBM in order of BASt.
Fig 4: Test Vehicle, Iveco Stralis with Additional Load on the 5th Wheel
The test velocity was 60-80 km/h and the measuring values were recalculated to 70 km/h.
According to the regulation the measuring values (LAmax) were rounded down to the next
integer value and 1 dB(A) must be subtracted for measuring uncertainties. This value (type
approval value: LR) has to be lower than the limit value specified for each tyre type.
3. Measuring Results
The legal limit value for steering axle tyres amounts to 76 dB(A). After the reducing
procedure described above the new tyre has a noise emission value (LR in Fig. 5,6,7) of
71 dB(A), which is 5 dB(A) below the limit value. The hot retreaded (Ihle) tyres - which were
build on carcasses of different manufacturers – vary between 71 and 72 dB(A), which is also
far below the limit value, see figure 5.
1
„Hot retreaded“ means that the profile is pressed into the hot rubber material in the vulcanisation process.
„Cold retreaded“ means the vulcanisation of a prefabricated profiled rubber band on the carcass.
Profilty
pee
Size
Steering Type
275/70
295/80
R22.5
LR
LA max dB(A)
80
315/60
R22.5
Limit Val.
Meas.
Val.
78
76
74
Dunlop New Tyre
Carcass Dunlop
Carcass Goodyear
Carcass Conti
502
IHLa21
IHLa11
IHLa15
403
IHLa12
SP351
New
Profil
70
e
IHLa22
72
Carcass Bridgestone
Carcass Michelin
Fig. 5: Tyre Noise, Steering Axle Tyres on Different Carcasses, Hot Retreaded (new left)
The drive axle tyre noise results of the hot retreaded tyres are shown in Figure 6. There are
also only small differences if the same profiles are realised on the tyres with different
carcasses. The type approval values are 0-3 dB(A) below the limit values and retreaded tyres
have noise emission values which were lower or as high as new tyres.
Tread pattern
Traction type
Tyre-size
295/80 R22.5
275/70 R22.5
80
315/60
315/80 R22.5
LRLR
Measuring value
34
534
HDR
Limit value
LA max [dB(A)]
78
76
74
44 44
New Tyre
Carcass Goodyear
428
XDE2+
Tread type 44
70
XDE2+
72
Carcass Dunlop
Carcasse Dunlop
Carcass
Conti
Carcass
Conti
Carcass
Conti
44
44
44428
428428
Carscass Bridgestone
Carcass Michelin
Fig. 6: Tyre Noise, Drive Axle Tyres on Different Carcasses, Hot Retreaded
Steering type
Traction type
Tread pattern
Tyre-size
315/80 R22.5
315/80
385/55
80
Measuring
value
LR
Limitvalue
76
74
72
BAN12
BAN11
HTR BHTR
BAN6
BAN4
BZA
BAN9
BAN8
BAN7
BAN3
BHDR
BAN5
BDE2
BDE2
BAN2
HDR
BAN1
70
BAN10
LA max [dB(A)]
78
Carcass Bridgestone M729
Conti new tyre
Carcass Conti HDR
Carcass Michelin XZE
Fig.7: Tyre Noise, Cold Retreaded Tyres: Steering, Drive (315) and Towed Axle Profile
(385)
The same statements made for hot retreaded tyres are valid for the cold retreaded tyres, see
figure 7. The increase of tyre noise for truck tyres amounts to about 2 dB(A) per 10 km/h, see
figure 8. So a truck which was measured in 7,5 m distance at 70 km/h with 74 dB(A) has a
noise emission of 76 dB(A) when driving its usual speed of 80 km/h, see figure 8.
82
BAN10
80
BAN1
BAN2
78
BAN3
dB
(A) 76
LR
BAN7
BAN8
74
BAN9
72
BAN4
BAN5
70
BAN6
68
BAN11
BAN12
66
60
70
Velocity
80
[km/h]
Fig. 8: Tyre Noise vs. Velocity, Cold Retreaded Tyres (Regression from 8 single tests)
4. Other Noise Emission Tests
In 2004 M+P in order of DWW (NL) measured several new truck tyres also according to the
above mentioned regulation 2001/43 EC at the test site of BASt in Sperenberg on the same
standardised road surface (ISO 10844) where the retreaded tyres were tested [4]. The noise
measuring results of the different (new and worn) tyres for the different axle positions are
shown in figure 9. In this investigation the steering axle tyres are also far below the legal limit
values (minus 5-6 dB(A) and they are nearly as silent as a non profiled tyre.
Drive
Steering
Tyre class C3 normal
(315/80 R22,5)
Towed
Tyre class C3 M&S
(315/80 R22,5)
Tyre class C3 normal
(385/65 R22,5)
Fig.9: Truck Tyre Noise Measurement Results [4]
With one exception the wider tyres for towed axles are also far
below the limit values. The tyre which is louder than the limit
value has a lot of holes in one side of the tread pattern, which
produces the typical sound of this tyre, see figure 10. The tyre is
still on the market. Transitory arrangements in the regulation
allow this.
Fig.10: Continental HTL Eco-plus
5. Conflict between Tyre Noise, Wet Grip and Rolling Resistance
Another question is the possible conflict between tyre noise, wet grip (safety) or rolling
resistance (fuel consumption and air pollution) assuming that the most interesting feature for a
truck operator is the mileage of a tyre (but this is based on personnel experience).
This possible impact was examined some years ago by the Federal Environmental Agency in
Germany [3]. From this study one can see that no conflict between the above mentioned tyre
features exists, see figure 11 and figure 12. A good tyre is good in many features - but maybe
not in price.
Rolling Resistance Coefficient cR [%] vs. Tyre Noise [dB(A)] Truck Tyres
[data source: TÜV/UBA research report 299 54 114, 2000]
2
1,9
steered-wheel tyres; 215/75 R17,5; class
C3; (medium trucks, local traffic)
1,8
1,7
Rolling Resistance Coefficient cR [%]
1,6
drive-wheel tyres; 215/75 R17,5; class
C3; M&S; (medium trucks, local traffic)
1,5
1,4
steered-wheel tyres; 275/70 R22,5; class
C3; (city bus)
1,3
1,2
1,1
drive-wheel tyres; 275/70 R22,5; class
C3; M&S (city bus)
1
0,9
0,8
steered-wheel tyres; 315/80 R22,5; class
C3; (heavy trucks, long distance traffic)
0,7
0,6
drive-wheel tyres; 315/80 R22,5; class
C3; M&S (heavy trucks, long distance
traffic)
0,5
0,4
0,3
summer tyres; 225/70 R15 C; class C2;
(light trucks, delivery traffic)
0,2
0,1
0
67,5 68 68,5 69 69,5 70 70,5 71 71,5 72 72,5 73 73,5 74 74,5 75 75,5 76 76,5
Tyre Noise [dB[A)]
Fig.11: Rolling Resistance and Tyre Noise for Different Truck Tyres
Fig.12: Wet Grip (Stopping Distance on Wet Road Surface) vs. Tyre Noise (225/70R15
tyres: ABS breaking of a light truck from 90 km/h to10 km/h, all other tyres: trailer
measurment)
5. Conclusions
•
•
•
•
•
•
•
•
•
•
•
•
Truck tyre noise is annoying, especially at nighttime near highways.
Drive axle tyres are much louder than steering axle or towed axle tyres.
New, cold and hot retreaded truck tyres were tested in coast-by tests acc. Reg. 2001/43EC.
All tyres fulfilled the requirements of the Regulation 2001/43EC (one not in a Dutch
study).
Tyre noise emissions are very different for the different profile types.
Tyres with the same profile but different carcasses used before retreading had nearly the
same tyre road noise emissions.
The differences of tyres for the same purpose (axle position) of different manufacturers
with different profile designs vary 2-3 dB(A).
Retreaded tyres were not louder but sometimes more silent than the comparable new tyres.
The noise emission values of all (retreaded and new) test tyres fell below the limit values
of the Regulation 2001/43EC, e.g. tyres with steering axle profile minus 3-6dB(A).
Compared to 70 km/h the tyre road noise is +2 dB(A) louder at 80 km/h, the usual truck
driving speed.
No difference was found between cold and hot retreaded tyres.
If retreaded tyres should be incorporated into the regulation, families of tyres have to be
defined.
6. Literature
[1]
BMVBW Hrsg.: Straßenbaubericht 2004, Bonn 2004
[2]
Glaeser, K.-P.; Beckenbauer, T.: Geräuschemissionen runderneuerter LKW Reifen,
BASt Report, 2004
[3]
TÜV/UBA, Report 29954114, München 2000
[4]
M+P: Tyre/road noise measurements of truck tyres, DWW 03.7.1, Delft 2004