Car tires are depicted with alphanumeric tire codes (in American English and Canadian English) or tire codes (in English, Australian English and others) printed (or molded) onto the tire sidewall. This code sets the tire dimension, and some key constraints, such as load-bearing ability, and maximum speed. Sometimes the inner wall contains information that is not included on the outer wall, and vice versa.
The code has evolved in complexity over the years, as is evident from a mixture of SI and imperial units, and ad-hoc extensions to letters and numbering schemes. New automotive tires often have ratings for attractiveness, treadwear, and temperature resistance (collectively known as Uniform Tires Quality rating (UTQG)).
Most tire sizes are provided using an ISO Metric measurement system. However, some pickup trucks and SUVs use Light Truck Numeric or Light Truck High Flotation systems.
Video Tire code
National technical standard rules
The European Tire and Rim Technical Organization (ETRTO) and the Tire and Launch Association (TRA) are the two organizations that affect national tire standards. The ETRTO objectives include harmonizing national tire and rim standards in Europe. The Tire and Rim Association, formerly known as The Tire and Rim Association of America, Inc., is an American trade organization that standardizes technical standards. In the United States, the Vehicle Safety Compliance Office, a component of the Department of Transportation, is one of the agencies assigned to enforce the Federal Vehicle Safety Standard (FMVSS). Canada has issued tire regulations, such as Vehicle Tire Safety Regulations SOR 95-148.
Maps Tire code
Explanation of tire code
The ISO Metric tire code consists of a series of letters and numbers, as follows:
- An optional letter (or letter) indicating the intended use or the vehicle class for the tire:
- P : Passenger Car
- LT : Light Truck
- ST : Custom Trailer
- T : Temporary (limited use for space saver "saver wheel))
P indicates that the tires are engineered for the TRA standard, and the absence of a letter indicates that the tires are engineered to the ETRTO standard. In practice, the standards of both organizations have evolved together and are quite interchangeable, but not completely, because the Load Index will be different for the same tire size.
- 3-digit : "The nominal width" of the tire in millimeters; the widest point of both sides outside (side wall to side). The surface of the tire that touches the road usually has a smaller width.
- /: Character slash for character separation.
- 2 or 3 digit number : "Aspect ratio" of the side wall height as the percentage of the width of the nominal portion of the tire. If the information is omitted, it is assumed 82% (if it is written, it should be like xxx/82). If the number is greater than 200, then this is the entire tire diameter in millimeters.
- An optional letter showing the tire speed rating. Alternatively, the letter may appear at the end, following the load index. If the letters here are Z , indicating a maximum speed of over 240km/h (149mph), then the more specific letters W or Y may appear after the load index (see speed ranking, below).
- An optional letter showing the construction of a tire cloth carcass:
- B : bias belt (where the side wall is the same material as the tread, leading to a rigid journey)
- D : diagonal
- R : radial
- if omitted, then it is a cross-ply
- number 1 or 2-digit : The inner diameter of the wheel specially designed for tires. There are rare exceptions of metric diameter tires, such as the use of size 390, which in this case will show wheels of 390 mm in diameter. Some tires are made for this size at this time. The amount may be longer when half-inch size is used, for example many heavy truck trucks now use 22.5-inch tires.
- 2 or 3 digit numbers : Loading index; see table below. Some light truck tires are approved for "dual use", ie they can be run in contiguous pairs. If so, separate load indexes will be specified for single and multiple uses. In the example shown in the light truck tire illustration, the tire has a 114 index load if used as a single tire, and a load index of 111 if it is used in double pairs. This unmarked tire is not safe for dual use.
- 1- or 2 digit/combo letter : Speed ​​rating; see table below
- Additional tags: See the subtitle below.
Flotation size
Some light truck tires follow the Light Truck Numeric or Light Truck High Flotation system, shown by the letters LT at the end and not the beginning of the sequence, as follows:
- Tire diameter is given for High Flotation tires and removed from Numeric tires.
- 2-digit number : Tire diameter in inches.
- x : Character separator.
- 3 or 4 digit number : The width of the section (sectional) of the tire in inches. If the tire diameter is not given, the section width ends with zero (eg, 7.00 or 10.50) showing an aspect ratio of 92%, while the section width does not end with zero (eg, 7.05 or 10.55) showing an aspect ratio of 82%. This aspect ratio often varies from the current tire manufacturer's specifications.
- Construction of tire fabric:
- B : bias belt
- D : diagonal
- R : radial
- 2-digit number : The inner diameter of the wheel rim designed to fit this tire.
- LT : Indicates that this is a Light Truck tire.
- The load index and speed rating are sometimes not mandatory for flotation sizes, but should be for any tire approved for road and road use.
- 2 or 3 digit numbers : Loading index; see table below.
- 1 or 2 digit/letter combination: Speed ​​rating; see table below.
- Additional tags: See the subtitle below.
For example, if the tire size has two sets of numbers (6-12, 5.00-15, 11.2-24), then the first number ( 5.00 -15) is the approximate width in inches, and the second number (5.00 - 15 ) is the rim diameter in inches.
If the tire size has three sets of numbers (15x6.00-6, 26x12.00-12, 31x15.50-15), then the first number ( 26 x12.00-12) is an approximate height in inches , the second number (26x 12.00 -12) is the approximate width in inches, and the third digit (26x12.00- 12 ) is the rim diameter in inches.
Load range
Mail Load Ranges on light truck tires show their ply ratings.
Loading index
The load index on a passenger car tire is a numerical code that sets the maximum load (mass, or weight) that each tire can carry. For the Load Range "B" tire, the ETRTO (ISO-Metric) standard assigns a load index rating to an inflation pressure of 36Ã, psi (250 kPa) (table below), while the P-Metric standard measures load capacity at a pressure of 35 psi ( 240 kPa). Both standards are slightly different from the capacity required for different inflation pressures.
While all ETRTO tires with the same load index will have the same maximum load, the P-Metric tires with the same load index may have different load capacities depending on the size of the tire. The TRA Inflation table should always be consulted when comparing the load capacity of P-Metric tires; Load index alone is not enough. Example: Standard Load Tire P205/50R15 has a load index of 84 and a load rating of 505 kg (1,113 lbs) at 35 psi (240 kPa). A P215/50R13 with the same load index of 84 has only a load rating of 495 kg (1.091 Â £), also at 35 psi (240 kPa).
ETRTO produces the Standard Manual (current edition 2010), which contains a number of specifications and tables. The load index table (G7 2010 page) lists the Load index of 0-45 kg (0-99 pounds) to 279-136,000 kg (615-299,829 pounds) (although apparently related to inflation pressure of 42 psi (290 kPa) it does not specify, but see Load Inflation Table). Table Load Inflation reference index load index inflation pressure between 22 psi (150 kPa) and 42 psi (290 kPa) at 1 psi (6.9 kPa) interval which is too large to include here.
Some longer letter-rate charge rate ranges for Light Truck Tires can be found in charts published by Goodyear Tire & amp; Rubber Company. As an example:
Speed ​​rating
Speed ​​symbol consists of one letter or A with one number. This shows the maximum speed at which the tire can carry loads according to the Load Index. The test method consists of tapping the tire against a large diameter metal drum to reflect the appropriate load, and running at an increasing speed within 10 km/h (6.2 mph) step in 10 minutes increments until the required speed of the tire has been met.
Prior to 1991, tire speed ratings were shown in tire size, before the "R" construction type. Available codes are SR (180 km/h, 112 mph), HR (210 km/h, 130 mph), VR (more than 210 km/h, 130 mph).
Tire rated speeds higher than 300 km/h (186 mph) are indicated by Y in brackets. Freight rating is often included in brackets, e.g. (86Y).
In many countries, legislation requires tires to be determined, and installed, to exceed the maximum speed of vehicles installed on them, in respect of their speed rating code (except for "temporary-use" backup tires). In some parts of the European Union, tires that are not suitable for a certain maximum speed of a car or motorcycle are illegal to install. The only exception is the M S tire, in which a warning sticker stating the maximum permissible speed should be placed in clear view of the driver in the vehicle. Some manufacturers will install speed governors if the vehicles are booked with tires rated below the maximum speed of the vehicle. In some parts of the European Union, for example Germany, it is permissible to install a tire with a lower speed rating code if the car manufacturer sets the tire with a very high speed rating in the registration documents and the vehicle will not reach this speed based on insufficient power. In this case it is possible to calculate the speed rating according to the formula.
Chart to Imperial tire conversion chart
R15
215/75/15 27,7 "x 8,5"
225/70/15 27,4 "x 8,9"
225/75/15 28,3 "x 8,9"
235/75/15 29.0 "x 9.3"
245/75/15 29,5 "x 9,6"
255/75/15 30.0 "x 10.0"
265/75/15 30,6 "x 10,4"
R16
205/85/16 29,7 "x 8,1"
215/75/16 28,7 "x 8,5"
225/70/16 28,4 "x 8,9"
225/75/16 29.2 "x 8.9"
235/70/16 29,0 "x 9.3"
235/85/16 31,7 "x 9.3"
245/70/16 29,5 "x 9,6"
245/75/16 30,5 "x 9,6"
Lebar Roda/Rim
To determine the range of permitted rim widths for a given tire size, the TRA Yearbook or manufacturer's guide should always be consulted for the special tire - no rule of thumb. Running a tire on the size or type of rims not approved by the manufacturer may lead to tire failures and loss of vehicle control.
Additional tags
When referring to pure geometry data, a short form of full notation is used. To take a general example, 195/55R16 would mean that the nominal width of the tire is about 195 mm at its widest point, the height of the tire sides is 55% of the width (107 mm in this example) and that the tire fits with a 16-inch (410 mm) diameter wheel. The code gives a direct calculation of the theoretical diameter of the tire. For sizes displayed as "T/A_W" use (2ÃÆ'â € "TÃÆ' â €" A/100) (WÃÆ'â € "25.4) for results in millimeters or (T * A/1270) W for results in inches. Take the general examples used above; (2/5/2012) (16/5) = 621 mm or (195ÃÆ'â € "55/1270) 16 = 24.44 inches.
This calculation is not commonly used to obtain outside diameter for regular vehicles. In fact, truck builders and off-road fans use it to find out the exact wheel diameter, which will fit into the wheel wells. For US vehicles, wheel well capacity is measured in inches, so when the outside tire diameter is calculated, it is usually compared to the well wheel index. This is done to prevent tires rubbing against the control arm and fenders.
Less commonly used in the United States and Europe (but often in Japan for example) is a notation that shows the full tire diameter instead of the high side aspect ratio of the sidewall. To take the same example, 16-inch wheels will have a diameter of 406 mm. Adding twice the tire height (2ÃÆ'â € "107 mm) makes the total tire diameter of 620 mm. Therefore, the 195/55R16 tire may be labeled 195/620R16 .
While this is theoretically ambiguous, in practice these two notations can be easily distinguished because the height of the sides of the automotive tire is usually much smaller than the width. Therefore when high is expressed as a percentage width, it is almost always less than 100% (and certainly less than 200%). Conversely, the vehicle tire diameter is always greater than 200 mm. Therefore, if the second number is over 200, it is almost certain that Japanese notation is used - if less than 200 then US/European notation is being used.
The diameter mentioned above is the theoretical diameter of the tire. The actual diameter of a special tire size can only be found in the TRA Annual Book or the manufacturer's data book. Note that cross sections and tire diameters are always determined when measured on wheels of a specified width; Different widths will produce different tire dimensions.
Example
Tires on BMW Mini Cooper may be labeled: P195/55R16 85H
- This is for passenger vehicles. However 'P' denotes P size of metric loads and changes in speed rating for P & amp; non-P tires.
- 195 - the nominal width of the tire is approximately 195 mm at its widest point
- 55 - indicates that the height of the tire's side wall is 55% of the width (107 mm)
- R - this is a radial tire
- 16 - This tire fits with the 16Ã, × (410 mm) wheel
- 85 - load index, maximum 515 kg (1,135 pounds) per tire in this case
- H - the speed index, this means the maximum allowed speed, here 210 km/h (130 mph).
The tire on the Hummer H1 may be labeled: 37X12.5R17LT
- 37 - 37Ã diameter diameter, in (940 mm)
- 12.5 - tires have a 12.5-inch (320 mm) cross section
- R - this is a radial tire
- 17 - This tire corresponds to the 17Ã wheel, (430 mm)
- LT - this is a light truck tire.
Historical Code Code
North America
Before 1964, all tires were made with a 90% aspect ratio. The tire size is determined as the width of the tire in inches and the diameter in inches - e.g. 6.50-15 .
From 1965 to early 70s, tires are made with an 80% aspect ratio. The size of the tires is further determined by the width of the inch and diameter in inches. To distinguish from the previous 90th ratio tires, decimal points are usually ignored from the width - e.g. 685-15 for the 6.85-inch tires.
Starting in 1972 the tire was determined by the load rating, using a letter code. In practice, tires with higher payload ratings are also wider tires. In this system the tire has a letter, optionally followed by "R" for radial tires, followed by aspect ratio, dash and diameter - C78-15 or CR78-15 for bias and radial respectively. Each wheel diameter has a separate load ranking sequence, so C78-14 and C78-15 do not have the same width. The 78% aspect ratio is typical for letter-size tires, although 70% is also common and a lower profile up to 50% is sometimes seen.
See also
- Bicycle Tires
- Motorbike tire
- Plus Size
- Speedometer errors caused by tire size variations.
- Tire making
- Uniform Tire Quality Uniform (UTQG)
- Wheel size
References
Source of the article : Wikipedia
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