Asia Pacific Commercial Vehicle Tire Pressure Guidance Notes and Pressure Recommendation Process 2014
Background The Giti Commercial Vehicle Tire Pressure Guide and Pressure Recommendation Consists of Two Parts: 1 st Part: Pressure Guide - introduces the pressure reference values for different vehicle models, load, and tire specifications. After gathering some simple information (vehicle model, gross vehicle weight, and tire specification), the corresponding pressure reference value can be calculated quickly and easily. 2 nd Part: Pressure Recommendation Process - introduces the specific process of pressure recommendation to help with understanding various methods and application. This is for professional use by qualified tire technicians. 1. Giti Commercial Vehicle Tire Pressure Guide (for easy use by dealers and fleets) Fast Search After the vehicle model, gross vehicle weight, and tire specification are known, the corresponding single tire load and recommended pressure can be searched easily from the Single Tire Load Table. Search Procedure Step 1: Select Vehicle Model 4x2 Truck/Bus 6x2 Truck (4 Front Wheels + 4 Rear Wheels) 6x4 Truck (2 Front Wheels + 8 Rear Wheels) 8x4 Truck (4 Front Wheels + 8 Rear Wheels) 4x2 Tractor + 2-Axle Trailer (1-1-2) 4x2 Tractor + 3-Axle Trailer (1-1-3) 6x4 Tractor + 3-Axle Trailer (1-2-3) 6x2 Tractor + 3-Axle Trailer (1-1-1-3) This material is for reference only. Giti Tire (China) Investment Company Ltd reserves the right of final interpretation. Step 2: Select Tire Specification Values within the orange boxes refer to tire specifications. Reference Values (kpa) 9.00R20 590 590 10.00R20 - - 11.00R20 - - 12.00R20 - - 10R22.5 590 590 11R22.5 - - 12R22.5 & 295 13R22.5 & 315 Step 3: Select Gross Vehicle Weight The gross vehicle weight is measured by t which stands for ton. Values within the yellow box refers to the vehicle weight. 10 tons 12 tons 14 tons Step 4: Select Wheel Position S stands for steering wheel, D stands for drive axle, and T stands for trailer wheel. The letters within the blue boxes refer to the wheel positions. 35 tons 45 tons 55 tons Wheel Position S D T S D T S D T Step 5: Search for Recommended Tire Pressure Use the information above to conduct a quick search of single tire loads and recommended pressure for each wheel position from the corresponding table. Information Source Accuracy Characteristics Suitable Staff Fast Search Relatively accurate and easy to use Sales staff, customer service, and junior technical service staff Page 1 Page 2
Example Detailed Data (Only for Reference) For a 4x2 truck/bus, if the gross vehicle weight is 16 t, tire specification is 12.00R20, and wheel position is steering wheel, the steering wheel load is found to be 2.22 t in the table below and the recommended tire pressure can be selected from the values in the green area of the corresponding column. This load is less than the maximum load designed for the tire as reflected by the vehicle travel limits table; it is within the safe area. If the gross vehicle weight is 22 t, tire specification is 12.00R20, and wheel position is drive axle, the drive axle load is found to be 4.07 t in the table below and the recommended pressure can be selected from the values in the yellow area of the corresponding column. This load is greater than the maximum load designed for the tire as reflected by the vehicle travel limits table; it is within the caution area. 4x2 Truck/Bus 1. 4x2 Truck/Bus 4x2 Drive Axle 4x2 Steering Wheel Gross vehicle weight (t) Schematic Diagram of a 4x2 Truck/Bus 10 tons 12 tons 14 tons 16 tons 18 tons 20 tons 22 tons 24 tons Wheel Position S D S D S D S D S D S D S D S D 1.58 1.71 1.79 2.10 2.00 2.50 2.22 2.89 2.43 3.29 2.64 3.68 2.85 4.07 3.07 4.47 10 tons 12 tons 14 tons 16 tons 18 tons 20 tons 22 tons 24 tons Wheel Position S D S D S D S D S D S D S D S D 1.58 1.71 1.79 2.10 2.00 2.50 2.22 2.89 2.43 3.29 2.64 3.68 2.85 4.07 3.07 4.47 9.00R20 590 590 590 660 590 830 660 1000 760 1000 830 1000 1000 10.00R20 620 620 620 620 620 690 620 900 620 1000 690 1000 760 870 11.00R20 620 620 620 620 620 620 620 790 620 930 620 1000 690 1000 760 12.00R20 660 660 660 660 660 660 660 660 660 790 660 930 660 1000 660 1000 10R22.5 590 590 590 660 590 830 660 1000 760 1000 830 1000 1000 11R22.5 620 620 620 620 620 690 620 900 620 1000 690 1000 760 870 12R22.5 & 295 620 620 620 620 620 790 620 930 620 1000 690 1000 760 13R22.5 & 315 660 660 660 660 660 660 660 790 660 930 660 1000 660 1000 9.00R20 590 590 590 660 590 830 660 1000 760 1000 830 1000 1000 10.00R20 620 620 620 620 620 690 620 900 620 1000 690 1000 760 870 11.00R20 620 620 620 620 620 620 620 790 620 930 620 1000 690 1000 760 12.00R20 660 660 660 660 660 660 660 660 660 790 660 930 660 1000 660 1000 10R22.5 590 590 590 660 590 830 660 1000 760 1000 830 1000 1000 11R22.5 620 620 620 620 620 690 620 900 620 1000 690 1000 760 870 12R22.5 & 295 620 620 620 620 620 790 620 930 620 1000 690 1000 760 13R22.5 & 315 660 660 660 660 660 660 660 790 660 930 660 1000 660 1000 2. 6x2 Truck (4 Front Wheels + 4 Rear Wheels) 6x2 Drive Axle 6x2 Steering Wheel Table: the color blocks in this table applies to 12.00R20 specification. The green area corresponds to vehicle loads and air pressures within the standard for safe driving; the yellow and red areas are out of the design limits of the tires, but sometimes can be seen in some developing countries. 4x2 Drive Axle 4x2 Steering Wheel 11 tons 13 tons 15 tons 17 tons 19 tons 21 tons 23 tons 25 tons 27 tons Wheel Position S D S D S D S D S D S D S D S D S D 0.92 1.83 1.08 2.17 1.25 2.50 1.42 2.83 1.58 3.17 1.75 3.50 1.92 3.83 2.08 4.17 2.25 4.50 Gross vehicle weight (t) 9.00R20 590 590 590 660 590 830 590 930 590 1000 590 590 590 660 10.00R20 620 620 620 620 620 690 620 870 620 1000 620 1000 620 1000 620 11.00R20 620 620 620 620 620 620 620 760 620 900 620 1000 620 1000 620 1000 620 12.00R20 660 660 660 660 660 660 660 660 660 760 660 870 660 1000 660 1000 660 1000 10R22.5 590 590 590 660 590 830 590 930 590 1000 590 590 590 660 11R22.5 620 620 620 620 620 690 620 870 620 1000 620 1000 620 1000 620 12R22.5 & 295 620 620 620 620 620 760 620 900 620 1000 620 1000 620 1000 620 13R22.5 & 315 660 660 660 660 660 660 660 760 660 870 660 1000 660 1000 660 1000 Page 3 Page 4
3. 6x4 Truck (2 Front Wheels + 8 Rear Wheels) 6x4 Drive Axle 5. 4x2 Tractor + 2-Axle Trailer (1-1-2) 4x2+2 Trailer Wheel 4x2+2 Drive Axle 6x4 Steering Wheel 4x2+2 Steering Wheel Steering Wheel (S) Drive Axle (D) Trailer Wheel (T) 18 tons 21 tons 24 tons 27 tons 30 tons 33 tons 36 tons 39 tons 42 tons 45 tons Wheel Position S D S D S D S D S D S D S D S D S D S D 1.87 1.78 2.07 2.11 2.26 2.43 2.46 2.76 2.65 3.09 2.85 3.41 3.04 3.74 3.24 4.07 3.44 4.39 3.63 4.72 9.00R20 590 590 590 660 660 830 760 1000 830 1000 1000 1000 1000 1000 1000 10.00R20 620 620 620 620 620 660 620 870 690 930 760 1000 870 1000 930 1000 1000 1000 11.00R20 620 620 620 620 620 620 620 760 620 870 690 1000 760 1000 830 1000 900 1000 12.00R20 660 660 660 660 660 660 660 660 660 720 660 830 660 930 660 1000 760 1000 830 1000 10R22.5 590 590 590 660 660 830 760 1000 830 1000 1000 1000 1000 1000 1000 11R22.5 620 620 620 620 620 660 620 870 690 930 760 1000 870 1000 930 1000 1000 1000 12R22.5 & 295 620 620 620 620 620 760 620 870 690 1000 760 1000 830 1000 900 1000 13R22.5 & 315 660 660 660 660 660 660 660 720 660 830 660 930 660 1000 760 1000 830 1000 30 tons 35 tons 40 tons 45 tons 50 tons 55 tons 60 tons 65 tons Wheel Position S D T S D T S D T S D T S D T S D T S D T S D T 2.01 2.09 2.20 2.23 2.44 2.60 2.44 2.78 3.00 2.65 3.13 3.40 2.86 3.47 3.80 3.08 3.81 4.20 3.29 4.16 4.60 3.50 4.50 5.00 10.00R20 620 620 620 620 660 720 620 870 930 690 1000 1000 760 1000 1000 1000 1000 1000 1000 11.00R20 620 620 620 620 620 660 620 760 830 620 870 1000 690 1000 1000 760 1000 1000 1000 1000 930 12.00R20 660 660 660 660 660 660 660 660 690 660 720 830 660 870 1000 660 1000 1000 690 1000 1000 760 1000 11R22.5 620 620 620 620 660 720 620 870 930 690 1000 1000 760 1000 1000 1000 1000 1000 1000 12R22.5&295 13R22.5&315 620 620 620 620 620 660 620 760 830 620 870 1000 690 1000 1000 760 1000 1000 1000 1000 930 660 660 660 660 660 660 660 660 690 660 720 830 660 870 1000 660 1000 1000 690 1000 1000 760 1000 4. 8x4 Truck (4 Front Wheels + 8 Rear Wheels) 8x4 Drive Axle 6. 4x2 Tractor + 3-Axle Trailer (1-1-3) 4x2+3 Drive Axle 4x2+3 Steering Wheel 4x2+3 Trailer Wheel 8x4 Steering Wheel Steering Wheel (S) Drive Axle (D) Trailer Wheel (T) 20 tons 25 tons 30 tons 35 tons 40 tons 45 tons 50 tons Wheel Position S D S D S D S D S D S D S D 2.00 1.50 2.25 2.00 2.50 2.50 2.75 3.00 3.00 3.50 3.25 4.00 3.50 4.50 9.00R20 590 590 660 620 760 830 900 1000 1000 1000 1000 10.00R20 620 620 620 620 660 690 720 930 870 1000 1000 1000 1000 11.00R20 620 620 620 620 620 620 660 830 760 930 830 1000 930 12.00R20 660 660 660 660 660 660 660 690 660 870 690 1000 760 1000 10R22.5 590 590 660 620 760 830 900 1000 1000 1000 1000 11R22.5 620 620 620 620 660 690 720 930 870 1000 1000 1000 1000 12R22.5 & 295 620 620 620 620 660 830 760 930 830 1000 930 13R22.5 & 315 660 660 660 660 660 690 660 870 690 1000 760 1000 Page 5 30 tons 35 tons 40 tons 45 tons 50 tons 55 tons 60 tons 65 tons 70 tons 75 tons Wheel Position S D T S D T S D T S D T S D T S D T S D T S D T S D T S D T 1.60 2.50 1.40 1.84 2.86 1.66 2.09 3.21 1.91 2.33 3.57 2.17 2.57 3.93 2.43 2.81 4.29 2.69 3.06 4.64 2.94 3.30 5.00 3.20 3.54 5.36 3.46 3.79 5.71 3.71 10.00R20 620 690 620 620 900 620 620 1000 620 620 1000 620 660 1000 660 760 790 870 930 1000 1000 1000 1000 1000 1000 11.00R20 620 620 620 620 760 620 620 930 620 620 1000 620 620 1000 620 660 1000 720 760 790 830 900 930 1000 1000 1000 12.00R20 660 660 660 660 660 660 660 760 660 660 900 660 660 1000 660 660 1000 660 660 1000 660 690 760 760 870 870 1000 11R22.5 620 690 620 620 900 620 620 1000 620 620 1000 620 660 1000 660 760 790 870 930 1000 1000 1000 1000 1000 1000 12R22.5&295 13R22.5&315 620 620 620 620 760 620 620 930 620 620 1000 620 620 1000 620 660 1000 720 760 790 830 900 930 1000 1000 1000 660 660 660 660 660 660 660 760 660 660 900 660 660 1000 660 660 1000 660 620 1000 660 690 760 760 870 870 1000 Page 6
7. 6x4 Tractor + 3-Axle Trailer (1-2-3) 2. Giti Commercial Vehicle Tire Pressure Recommendation (for professional use) 6x4+3 Trailer Wheel 6x4+3 Steering Wheel 6x4+3 Drive Axle Pressure Recommendation Procedure: Steering Wheel (S) Drive Axle (D) Trailer Wheel (T) 1. Learn Basic Vehicle Information 2. Specify Single Tire Load 3. Recommend Tire Pressure 35 tons 45 tons 55 tons 65 tons 70 tons 75 tons 80 tons 85 tons 90 tons Wheel Position S D T S D T S D T S D T S D T S D T S D T S D T S D T 2.15 1.95 1.28 2.59 2.19 1.87 3.03 2.42 2.47 3.47 2.65 3.07 3.69 2.77 3.36 3.91 2.89 3.66 4.14 3.01 3.96 4.36 3.12 4.26 4.58 3.24 4.56 10.00R20 620 620 620 660 590 460 870 660 690 1000 760 1000 1000 870 1000 1000 900 1000 1000 1000 1000 11.00R20 620 620 620 620 620 620 760 620 620 900 690 830 1000 760 1000 1000 790 1000 1000 830 1000 1000 1000 12.00R20 660 660 660 660 660 660 660 660 660 760 660 690 830 660 830 900 660 930 1000 690 1000 1000 720 1000 1000 760 1000 11R22.5 620 620 620 660 590 460 870 660 690 1000 760 1000 1000 870 1000 1000 900 1000 1000 1000 1000 12R22.5&295 13R22.5&315 620 620 620 620 620 620 760 620 620 900 690 830 1000 760 1000 1000 790 1000 1000 830 1000 1000 1000 660 660 660 660 660 660 660 660 660 760 660 690 830 660 830 900 660 930 1000 690 1000 1000 720 1000 1000 760 1000 8. 6x2 Tractor + 3-Axle Trailer (1-1-1-3) 6x2+3 Drive Axle 1. Learn Basic Vehicle Information First, learn the following basic vehicle information: Vehicle Model - to calculate single tire load Gross Vehicle Weight - to calculate single tire load (vehicle weight + cargo weight) Tire Specification for Each Wheel Position - to recommend tire pressure The following commercial vehicle models are commonly seen in developing countries: Steering Wheel (S) Drive Axle (D) Trailer Wheel (T) 6x2+3 Trailer Wheel 6x2+3 Steering Wheel Gross vehicle weight (t) Vehicle Model Common Model Classification Standard Model Classification 4 Front Wheels + 4 Rear Wheels 2 Front Wheels + 8 Rear Wheels 4 Front Wheels + 8 Rear Wheels 4x2 Truck/Bus 6x2 Truck 6x4 Truck 8x4 Truck 35 tons 45 tons 55 tons 65 tons 70 tons 75 tons 80 tons Wheel Position S D T S D T S D T S D T S D T S D T S D T 1.66 1.90 1.73 1.98 2.70 2.19 2.30 3.50 2.65 2.62 4.30 3.11 2.78 4.70 3.34 2.94 5.10 3.57 3.10 5.50 3.80 10.00R20 620 620 620 620 790 620 620 1000 760 660 1000 720 1000 830 1000 900 1000 11.00R20 620 620 620 620 720 620 620 1000 690 620 1000 870 660 1000 720 1000 760 1000 12.00R20 660 660 660 660 660 660 660 870 660 660 1000 720 660 1000 830 660 900 660 1000 11R22.5 620 620 620 620 790 620 620 1000 760 660 1000 720 1000 830 1000 900 1000 12R22.5&295 13R22.5&315 620 620 620 620 720 620 620 1000 690 620 1000 870 660 1000 720 1000 760 1000 660 660 660 660 660 660 660 870 660 660 1000 720 660 1000 830 660 900 660 1000 Page 7 Vehicle Model Common Model Classification Standard Model Classification 1-1-2 1-2-2 1-1-3 1-2-3 1-1-1-3 4x2 Tractor + 2-Axle Trailer 6x4 Tractor + 2-Axle Trailer 4x2 Tractor + 3-Axle Trailer 6x4 Tractor + 3-Axle Trailer 6x2 Tractor + 3-Axle Trailer Page 8
2. Specify Single Tire Load Measurement 1: Axle-by-Axle Weighing This method can be used when the axle-by-axle weighing conditions are met. Accurate single tire load is obtained by using the axle-by-axle weighing method. kg For Example: For a 4x2 tractor + 3-axle trailer, the following results are obtained by weighing: Weight of the Steering Axle A = 7.7 t Weight of the Whole Vehicle B =65 t Weight of the Trailer Axle C = 39.5 t Drive Axle D = B A C = 65 t - 7.7 t - 39.5 t = 17.8 t i) Truck/Bus Weighing the Steering Axle A: Place the steering axle on the weighbridge while leaving the drive axle out of the weighbridge. Applicable Models: Then: Single Tire Load of Steering Wheel = 7.7 t/2 = 3.85 t Single Tire Load of Drive Wheel = 17.8 t/4 = 4.45 t Single Tire Load of Trailer Wheel = 39.5 t/12 = 3.29 t Weighing the Whole Vehicle B: Place both the steering axle and the drive axle on the weighbridge to weigh the whole vehicle. Weighing the Drive Axle C: (Repeated weighing experiments prove that A+C=B, i.e. the sum of the loads of each axle is equal to the whole vehicle load) 4x2 Truck/Bus 6x2 Truck (i.e. 4 front wheels + 4 rear wheels) 6x4 Truck (i.e. 2 front wheels + 8 rear wheels) 8x4 Truck (i.e. 4 front wheels + 8 rear wheels) kg Information Source Axle-by-Axle Weighing Accuracy Characteristics Suitable Staff This is the most accurate method. However, axle-by-axle weighing conditions are required. R&D staff and technical service staff Single Tire Load of Steering Wheel = A/total number of tires on steering axle Single Tire Load of Drive Axle = C/total number of tires on drive axle ii) Road Train Measurement 2: Wheel Load Measuring Instrument This method is one of the most accurate measurement methods. 1. Use wheel load measuring instrument (weigh cell) for weighing. 2. The load of each tire can be weighed by the wheel load measuring instrument. 50 45 55 0 kg 5 10 15 First, weigh A (weight of the steering axle) Second, weigh B (weight of the whole vehicle) Third, weigh C (weight of the trailer axle) Applicable Models: 4x2 Tractor + 2-Axle Trailer (i.e. 1-1-2) 6x4 Tractor + 2-Axle Trailer (i.e. 1-2-2) 4x2 Tractor + 3-Axle Trailer (i.e. 1-1-3) 6x4 Tractor + 3-Axle Trailer (i.e. 1-2-3) 6x2 Tractor + 3-Axle Trailer (i.e. 1-1-1-3) Since the sum of the loads of each axle is equal to the whole vehicle load, the weight of the drive axle can be calculated as D = B - A - C Single Tire Load of Steering Wheel = A/total number of tires on steering axle Single Tire Load of Drive Wheel = D/total number of tires on drive axle Single Tire Load of Trailer Wheel = C/total number of tires on trailer axle Causes of Deviation between the Set Value and the Measured Value: Uneven load distribution (front and rear, left and right, load type) Overall diameters of the dual tires are different from each other Different tire pressure Deformation caused by overloading Road slope 50 45 55 0 kg 5 10 15 Information Source Wheel load measuring instrument method Accuracy Characteristics Suitable Staff Simulation boards Accurate with a visual display of data for each wheel position Wheel load measuring instrument R&D staff and technical service staff Page 9 Page 10
3. Recommend Tire Pressure Measurement 3: Vehicle Wheelbase Calculation After the single tire loads are specified, it is possible to determine if the tires are overloaded: This method can be used when the axle-by-axle weighing conditions cannot be met. However, it is necessary to know the gross vehicle weight, weight of the empty vehicle, axle weight of the empty vehicle, cargo weight, and wheelbase. Single Tire Load Maximum Load of Tire Specification Single Tire Load > Maximum Load of Tire Specification Not Overloaded Overloaded For Example: Take the 2 front wheels + 8 rear W (20,000 kg) The maximum load carrying capacity of the tire can be found in national standards, Giti Tire s Technical Knowledge of All Steel Tires Manual, or on the side of the tire: wheels vehicle as example. MAX LOAD SINGLE - Maximum safety load for single tire MAX LOAD DUAL - Maximum safety load for single tire of dual tires Given: Weight of Empty Vehicle = 10 t Deadweight = 20 t A (6,000 mm) L (600 mm) Not Overloaded Total Weight = 30 t There are two ways to set the pressure: Refer to Giti Tire s Technical Knowledge of All Steel Tires Manual Load on Front Axle of Empty Vehicle = Wfe (4,000 kg) Refer to the pressure recommendations of the vehicle manufacturer (usually these recommendations can be found in the user manual) Load on Front Drive Axle of Empty Vehicle = Wd1e (3,000 kg) Load on Rear Drive Axle of Empty Vehicle = Wd2e (3,000 kg) then: Load on Front Axle: WF = Wfe + (W L/A) = 4,000 + (20,000 600/6,000) = 4,000 + 2,000 = 6,000 kg Load on Front Drive Axle: WD1 = Wd1e + (W-W L/A)/2 = 3,000 + (20,000-2,000)/2 = 3,000 + 9,000 = 12,000 kg Load on Rear Drive Axle: WD2 = Wd2e + (W-W L/A)/2 = 3,000 + (20,000-2,000)/2 = 3,000 + 9,000 = 12,000 kg Single Tire Load of Front Axle = WF/2 = 6,000/2 = 3,000 kg Single Tire Load of Rear Axle = WD1/4 = WD2/4 = 12,000/4 = 3,000 kg Special Note: If the vehicle is mainly driven on highways, an additional 10% increase in pressure is recommended to avoid damage to tires due to overheating. If the vehicle is mainly driven on bad roads, an additional 10% decrease in pressure is recommended to reduce damages caused by cuts and impacts. Overloaded Excessive tire pressure due to overloading is extremely dangerous. When traveling, tires are subject to damage from the road such as impact and friction which can lead to tire blowouts. Generally, the safety pressure limit is 1,000 kpa. In Europe, America, Japan, and Korea, special permits are required to use high pressure containers above 1,000 kpa. For safety reasons, tire manufacturers will not recommend tire pressure for overloading conditions. Summary: Information Source Vehicle Wheelbase Calculation Accuracy Characteristics Suitable Staff Relatively accurate. However, the vehicle length needs to be measured and the calculation process can be complicated. R&D staff and technical service staff 1. Learn Basic Vehicle Information Vehicle Model Gross Vehicle Weight Tire Specification 2. Specify Single Tire Load 1: Axle-by-axle weighing method 2: Wheel load measuring instrument method 3: Vehicle wheelbase calculation method 3. Tire Pressure Recommendation Refer to Giti Tire s Technical Knowledge of All Steel Tires Manual Refer to the tire pressure recommendations of the vehicle manufacturer Page 11 Page 12
When Tire Pressure Value Is Determined, Be Sure To Maintain It! NOTES: Giti Tire can provide a tire pressure maintenance flip chart when needed. A new tire pressure label manual is also available! Page 13 Page 14
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