When Z-speed rated tires were first introduced, they were thought to reflect the highest tire speed rating that would ever be required, in excess of 240 km/h or 149 mph. While Z-speed rated tires are capable of speeds in excess of 149 mph, how far above 149 mph was not identified. That ultimately caused the automotive industry to add W- and Y-speed ratings to identify the tires that meet the needs of new vehicles that have extremely high top-speed capabilities.

While a Z-speed rating still often appears in the tire size designation of these tires, such as 225/50ZR16 91W, the Z in the size signifies a maximum speed capability in excess of 149 mph, 240 km/h; the W in the service description indicates the tire's 168 mph, 270 km/h maximum speed.

Matthew Kenney says:

Greg Urritia found:

Choices in a H or higher rated tire are better from Continental but they are also more expensive.

General has a single V rated tire in 15 inch.
195/55R15, 23.4 inch diameter at $67.56 each under the Racer Contingency  program

H-rated tires that I'm considering from General include
175/65R15, 24 diameter at $59.59
205/65R15, 25.5 diameter at $61.23 

I was able to come up with another H-Rated Tire (and there aren't many to choose from in a 15 inch). This time I ordered up a pair of 215/65-15 Nankang RX-615. 
 26.2 inch diameter, .

I bought a set of H-Rated General Grabber 207/70-15, 26.3 inch diameter tires for our base line rear meats

                                                         TIRES and the 36hp Challenge( and 130 Club VW Racers)

                                                                              Common Question Answers

NOTE: ALWAYS refer to the sanctioning body (USFRA, ECTA, TEXAS MILE ) rules and regulations for the most current and up to date

         guidelines. Information listed below is for general information only and may not represent the most up to date rule changes!

130 Mile Per Hour Club (USFRA) and similar ECTA and TEXAS MILE categories require H-Rated ( to 130 mph ) marked tires in very good condition to be fitted to all four wheels when running in land speed racing events. 36hp engine powered Volkswagens that have not achieved a speed of 100 miles per hour in previous time trials are allowed to run S-Rated ( to 112 mph ) tires up to the time they exceed 100 miles per hour, at which time it is necessary to switch to the higher H rated tires for all remaining passes.

For 2009, rule changes have mandated that all 130 Mile Per Hour Club racers including ALL 36hp Challenge racers install METAL VALVE STEMS in wheels equipped with tubeless tires or TUBES with METAL VALVE STEMS with NUTS inside tube type tires. Be sure to bring your car ALREADY equipped with these updates so you will be able to pass tech inspection. These types of components are NOT READILY AVAILABLE for purchase in the small towns where racing occurs so please come prepared.

Where to find:

S-Rated 165/80 x 15” tires- Usually 165 x 15 S rated tires, the most common VW size tire can be ordered through your local tire dealers( R-Rated tires are NOT LEGAL in 36hp Racing! Do not order R-Rated tires! ). Allow a week or more for delivery of special order tires( and metal valve stemmed tubes if needed!). Your nearest EMPI accessory dealer can also order S rated tires in 135/145 and 165 x 15 sizes. Contact EMPI at www.empius.com for local dealer contact information. Many tire sources can also be found in HOT VW”s, Ultra VW, Volks World and VWMA magazines. S-Rated 165/80 x 15 tires can also be purchased from www.tirerack.com and www.cokertire.com via the internet if not available locally.

http://www.discounttirezone.com/Falken-Ziex-ZE-912_c_336-1.html

H-Rated 15” tires- If your VW is not a 36hp Challenger or you expect to be running your 36hp Challenge VW above 100 miles per hour, street legal Hoosier H-Rated tires are available in a selection of narrow sizes for 15” wheels. Hoosier’s Pro Street Radial series tires are designed for rim widths of 5-6 inches and come in diameters from 22.5 to 25.9 inches. In addition, five different manufacturers of drag racing “Front Runner” tires legal for use on all four wheels in 130 MPH Club street car type events are available through a variety of other sources via the internet and mail-order. The two most common are www.jegs.com and www.summitracing.com . NOTE: Front Runner style tires should NEVER be driven on the street and are NOT LEGAL for street use!

Front Runner 15” tires- Front Runner tires for 15” wheels are available in a wide variety of overall tire diameters ranging from 22 to 27 inches. All Front Runner tires are designed for rim widths of 3.5-4 inches(most VW rims are 4 and 4.5 inches ). When installed on the wider VW rims, the slight spreading effect will make the tire “slightly shorter” so measuring the circumference of the tire when determining your actual gear ratios will provide greater accuracy in determining theoretical top speed and shift points than using the published diameter alone. Front Runner tires also provide a narrower front profile along with less friction ( i.e. traction ) which will improve your top speed when compared to wider more common street tires. Again, these tires are not street legal and should “never” be used on public roads or highways!

Listed below are sites where you can view the tire information on available H-Rated and Racing tires:

Hoosier Racing Tires-www.hoosiertire.com  : Both street legal 15” radials(H-Rated), Formula V and drag racing Front Runners available in a wide       variety of heights and widths. Hoosier provides the best overall selection in sizing, application and fitment information!

Front Runner Tires(can be used front or rear-DO NOT use on the street-UNSAFE ! ! !)

GoodYear Racing Tires-www.jegs.com/p/GoodYear  : Front Runner tires for racing only.

Mickey Thompson Racing Tires-www.uprproducts.com : Front Runner tires for racing only.

M&H Racing Tires- www.mandhtires.com  : Front Runner tires for racing only.

Phoenix Racing Tires- www.jegs.com/p/Phoenix+Drag+Tires  : Front Runner tires for racing only.

Moroso Racing Tires- www.jegs.com/p/Moroso  : Front Runner tires for racing only.

Tire Diameter Formula: 165 / 80 x 15 tire

                                165(tire size) divided by 25.4(formula) = 6.49 inches

                                6.49 inches times 80(sidewall profile) = 5.192

                                5.192 times 2(two sidewall heights on each tire) = 10.38 inches

                                10.38 inches plus 15”(wheel rim diameter) = 25.38 inches(tire

                                 diameter)

Moon Disc Hubcaps: Legal in all classes but must be securely fastened with 6 screws if mounted to wheel rim or 3 D’zus fastners if mounted to tabs welded to inner wheel lip.

Caution: If moon disc style hubcap is mounted with screws, inner tubes(with metal valve stems) are highly recommended to prevent slow leaks where tire bead contacts mounting screws.

Wheel rim size: Although 15 inch VW rims are most common, other wheel diameters (13”,14”,16”) can be used in all classes except the 36hp Stone Stock category. Aluminum rims are allowed(except Stone Stock). Optional rim diameters also allow additional H-Rated tires selections.

TIRE PRESSURES:  Tire pressures on the salt should be set at 50 P.S.I. for racing ( front and back). Be sure to adjust your pressures up before coming to race if trailering or adjust PRIOR to tech inspection if driving your VW. This is a SAFETY item to insure tubeless tires do not separate from the wheel bead and also reduces the tires rolling resistance for higher speed.