Connecting South Dakota and the Nation
Effect of Wide-Base Super
Single Tires on Pavements
David Huft, SDDOT Research Program Manager
AASHTO Research Advisory Committee Meeting
Madison, WI July 22, 2014
SD2012-01 Effect of Wide-Base
Super-Single Tires on Pavements
• Suggested by SD
Trucking Association
• Hoped to lift 500
lb/in restriction on
445/455 mm tires
• 5-month project
• Work by Hao Wang
From Priest & Trimm, TRR 1949
Wide-Base Tire Characteristics
• Introduced to North
America in 1982 to
replace dual tires
• Design for high-speed
long-distance carrier
• Reduced fuel
consumption
• Reduced tire recycling
• Increased payload
• Better ride comfort
and vehicle handling
Dual/ 275
1980
385
1982
2000
2002
2000
425
445/455
495
Early & Recent Wide-Base Tires
Early Generation
• 385/65R22.5, 425/65R22.5)
New Generation
• 445/50R22.5, 455/55R22.5
• High inflation pressure
(790-890kPa)
• Small contact area
• High contact stress
• High damage ratios
•
•
•
•
• 1.5-2.0 for rutting
• 2.0-4.0 for fatigue cracking
New crown architecture
15-18% wider than 1st gen
Reduced tire pressure
Damage ratios vary by:
• pavement structure
• damage type
• climate condition
(Virginia Smart Road 2000;
Europe COST334 2001; Canada
2004; NCAT 2006; ILDOT 2008;
FLDOT 2010)
Problem Statement
• In South Dakota, wide-base tires may be generally
substituted for standard duals, but the legally allowed
weight on single axles is reduced
• 17,500 lb for 445mm tires, 18,000 lb for 455 mm tires
• 20,000 lb for dual-tire configurations
• Previous studies involving laboratory tests, field tests,
and modeling have generated mixed results
• It was unclear whether results are applicable to the full
range of road surfaces (including unpaved) that exist on
state and local highways in South Dakota
Objectives
• Based on others’ research, assess effects of allowing
20,000 pound loads on single axles equipped with
445mm and 455mm wide-base tires on state and local
roads in South Dakota
• Assess need for additional research involving physical
testing or modeling
Major Research Tasks
• Extensive Literature
Review
• State Survey and
Interview
• Select Most Pertinent
Studies
• Calculate Damage
Ratios
• Assess Impact of
Policy Change
• Assess Additional
Research Needs
Selection of Most Pertinent Studies
Studies on wide-base tires
Similar Pavement Design in
South Dakota
Quebec Ministry of Transportation
(Pascale et al. 2004)
TonS
(Thin on Strong: 2 to 5 in. ACP on >
UTC/Nextrans Study (Al-Qadi and Wang
8 in. granular base)
2010; Wang and Al-Qadi 2011)
NCAT Study (Priest and Timm, 2006)
Ontario Ministry of Transportation
(Ponniah et al. 2006)
THK
(Thick: 5 to 10 in. ACP w/ granular
base)
Florida DOT Study (Greene et al. 2010)
Illinois DOT Study (Al-Qadi and Wang
2009)
FD
(full-depth: > 10 in. ACP w/no
granular base)
Tire-Pavement
Contact Area and Stress
1500
Transverse Contact Stress
(kPa)
Vertical Contact Stress (kPa)
(Wang and Al-Qadi 2009; 2011)
1000
500
Dual-tire Assembly
Wide-base 455
0
0
1
2
3
4 5 6
Tire ribs
7
8
9 10 11
400
300
200
100
Dual-tire Assembly
Wide-base 455
0
0
1
2
3
4
5 6 7
Tire ribs
8
9 10 11
Damage Ratios
on Thin & Thick Asphalt Pavement
Distress
Thin Asphalt
Thick Asphalt
1.68-2.82
0.86-1.26
N/A
0.16-0.67
Primary Rutting
1.35-1.77
1.05-1.27*
Subgrade Rutting
1.31-2.35
N/A
Fatigue Cracking
Top-Down Cracking
References
Wang and Al-Qadi, 2011 Greene et al. 2010
Pascale et al. 2004
Ponniah et al. 2006
Combined Damage Ratios
Pavement Type
Wide-base 455 vs.
Dual tires
Wide-base 445 vs.
Dual tires
Range
Average
Range
Average
1.08
NA
NA
0.88
0.76-1.41
1.08
1.88
NA
NA
Full-depth (FD) 0.85-1.32
Thick asphalt
0.69-1.07
(THK)
Thin asphalt on
strong base 1.45-2.31
(TonS)
SB154: Allows 445/455 mm Tires
on Major SD Highways
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and “any locally designated highway within
the corporate limits of any municipality
adjacent to the Interstate highway system”
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Future Work
• Analyze impact on full
range of road surfaces
(including unpaved) in SD
• Quantify possible increase of life-cycle agency
cost by allowing equal load limit on widebase single tires and dual tires on other state
and local roads
• Consider three important contributing factors
to pavement damage ignored in previous
studies: unbalanced loads between dual tires,
wheelpath wandering, and dynamic loading
Keys to Project Success
• Active support of SD trucking industry
• Political urgency
• Multi-disciplinary technical panel
• Relevant research by done others
• Availability of experienced researcher
Questions?
•
•
•
•
•
Please contact
David Huft
SDDOT Research
Program Manager
605.773.3358
dave.huft@state.sd.us