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Thread: I need facts, what's your speed...

  1. #1
    Registered User Caen Fred's Avatar
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    Default I need facts, what's your speed...

    What tire speed rating are you using, most of the 225x60x14 left are of the "T" rating type, have any toughts about using "T" over "H" tire's rating ?
    I think that those tires are build with a slight( read big) tolerence, and you?

    Thanks for your help, as usual, Fred
    vive la Franze, vive les Z, vive ZmeFly

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    Default well heres how it goes

    S = 112
    T = 118
    H = 130


    as you can see with the different ratings comes a different speed rating, you could go to any tire shop on the web and they will be able to tell you in detail.

    aslo with a higher speed rating comes a better grip and tighter side walls do to a softer compound in the tire and more sidewall bands for strength especially in the lower profile types.

    i have noticed a big difference in a H to Z rated tire. handling definetly changes.

    i dont think you would notice to much difference between a T and an H. depending on the manufacuter.

  3. #3
    Registered User Caen Fred's Avatar
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    Default

    Thank's that's a start.

    What I need is testimonial here.

    Any Z week-end racer on this site had "T" rating on their Z and suffer an horror story of blowing tire, runing at full speed ...
    Or you never had any side effect other than less than perfect handling ?

    thank you, Fred
    vive la Franze, vive les Z, vive ZmeFly

  4. #4
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    Default a better description

    speed ratings, and UTQG ratings,


    Using a P195/60R15 87S tire size as our example, the 87S at the end of the size represents the tire’s service description. A service description identifies the tire’s load index and speed rating. Service Descriptions are required on all speed rated (except for Z-speed rated) tires manufactured since 1991.

    The first two digits (87S) represent the tire’s load index and are followed by a single letter (87S) identifying the tire’s speed rating.

    Load Index

    P195/60R15 87S - The load index (87) is the tire size’s assigned numerical value used to compare relative load carrying capabilities. In the case of our example the 87 identifies the tires ability to carry approximately 1,201 pounds.

    The higher the tire’s load index number, the greater its load carrying capacity.

    89 = 1,279 pounds
    88 = 1,235 pounds
    87 = 1,201 pounds
    86 = 1,168 pounds
    85 = 1,135 pounds

    A tire with a higher load index than that of the original equipment tire indicates an increase in load capacity. A tire with a load index equal to that of the original equipment tire indicates an equivalent load capacity. A tire with a lower load index than the original equipment tire indicates the tire does not equal the load capacity of the original.

    Typically, the load indexes of the tires used on passenger cars and light trucks range from 70 to 110. Load Index Pounds Kilograms
    Load Index Pounds Kilograms
    71 761 345 91 1356 615
    72 783 355 92 1389 630
    73 805 365 93 1433 650
    74 827 375 94 1477 670
    75 853 387 95 1521 690
    76 882 400 96 1565 710
    77 908 412 97 1609 730
    78 937 425 98 1653 750
    79 963 437 99 1709 775
    80 992 450 100 1764 800
    81 1019 462 101 1819 825
    82 1047 475 102 1874 850
    83 1074 487 103 1929 875
    84 1102 500 104 1984 900
    85 1135 515 105 2039 925
    86 1168 530 106 2094 950
    87 1201 545 107 2149 975
    88 1235 560 108 2205 1000
    89 1279 580 109 2271 1030
    90 1323 600 110 2337 1060


    Speed Rating

    P195/60R15 87S - The tire speed rating (S) is the maximum speed for which the tire is rated. For example, the “S” rating identifies speeds up to 112 mph (180 km/h).

    It is important to note that speed ratings only apply to tires that have not been damaged, altered, under-inflated or overloaded. Additionally, most tire manufacturers maintain that a tire that has been cut or punctured no longer retains the tire manufacturer’s original speed rating, even after being repaired.

    In Europe, where selected highways do not have speed limits and high speed driving is permitted, speed ratings were established to match the speed capability of tires with the top speed capabilities of the vehicles to which they are applied. Speed ratings are established in kilometers per hour and subsequently converted to miles per hour (which explains why speed ratings appear established at “odd” mile per hour increments). Despite the tire manufacturer’s ability to manufacturer tires capable of high speeds, none of them recommend the use of their products in excess of legal speed limits.

    Speed ratings are based on laboratory tests where the tire is pressed (to reflect its required load) against a large diameter metal drum and run at ever increasing speeds (in 6.2 mph steps in 10 minute increments) until the tire’s required speed has been met.

    Speed Rating - Miles/Hour - Kilometers/Hour - Typical Use N=87 MPH, 140km/h, Spare Tires U=124 MPH, 200km/h
    P=93 MPH, 150km/h H=130 MPH, 210km/h, Sport Sedans
    Q=99 MPH, 160km/h, Winter, LT Tires V=149 MPH, 240km/h, Sports Cars
    R=106 MPH, 170km/h, LT Tires Z=149 MPH, 240km/h and over, Sports Cars
    S=112 MPH, 180km/h W=168 MPH, 270km/h, Exotic Sport Cars
    T=118 MPH, 190km/h Y=186 MPH, 300km/h, Exotic Sport Cars


    *Today, the Z-speed rating is the only speed rating that is still branded “within” the tire size, as in P225/50ZR16. All other speed ratings are shown in the tire’s service description.

    When Z-speed rated tires were first introduced, they were thought to reflect the highest speed rating that would ever be required. Since that time the automotive industry has found it necessary to add W- and Y-speed ratings (indicated in the tire’s service description) to identify the tires that meet the needs of new vehicles that have extremely high, top speed capabilities.
    Miles/Hour Kilometers/Hour
    P225/50ZR16 149+ 240+
    P225/50ZR16 91W 168 270
    P225/50ZR16 91Y 186 300


    While all Z-speed rated tires are capable of speeds of 149 mph and above, prior to the W- and Y-speed ratings were identified in the service, how far above 149 mph was not identified.

    Prior to 1991, the most popular speed ratings were “S,” “H” and “V.” However, while the speed capabilities of S- and H-rated tires still indicate the same speeds as before, the V-speed rating has been modified. Previously a V-speed rated tire with the “V” branded “within” the tire size indicated that the tire was capable of 130+ miles per hour as indicated below:
    Miles/Hour Kilometers/Hour
    P225/50SR16 112 180
    P225/50HR16 130 210
    P225/50VR16 130+ 210+


    this covers the UTGQ rating, which also talks little about heat ratings and life of a tire, theres not a lot here but remember the higher the heat rating the better the tire would be to resist failure running at constant high speeds.



    The Department of Transportation requires each manufacturer to grade its tires under the Uniform Tire Quality Grade (UTQG) labeling system and establish ratings for treadwear, traction, and temperature resistance. These tests are conducted independently by each manufacturer following government guidelines to assign values that represent a comparison between the tested tire and a control tire. While traction and temperature resistance ratings are specific performance levels, the treadwear ratings are assigned by the manufacturers following field testing and are most accurate when comparing tires of the same brand.

    Treadwear

    Treadwear receives a comparative rating based on wear rate of the the tire in field testing following a government specified course. For example, a tire grade of 150 wears 1.5 times as long as a tire graded 100. Actual performance of the tire can vary significantly depending on conditions, driving habits, care, road characteristics, and climate.

    Traction

    Straight-a-head wet braking traction has been represented by a grade of A, B, or C with A being the highest. In 1997 a new top rating of "AA" has been introduced to indicate even greater wet braking traction. However, due to its newness, this grade will probably be applied initially to new tire lines as they are introduced and later to existing lines which excel in wet braking, but had been limited to the previous top grade of "A". Traction grades do not indicate wet cornering ability.

    Temperature

    Temperature resistance is graded A, B or C. It represents the tire's resistance to the heat generated by running at high speed. Grade C is the minimum level of performance for all passenger car tires as set under Federal Motor Vehicle Safety Standards. This grade is established for a tire that is properly inflated and not overloaded.

  5. #5
    Registered User Caen Fred's Avatar
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    Default

    Woah, talking about facts... so I guess it will explode... right?

    Thank's, Fred
    vive la Franze, vive les Z, vive ZmeFly

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