General Tire info- Everyone should know!

[kaybeejay]

Here's some tire info you might find useful. Some is from http://www.tirerack.com, and some is general knowledge.Sidewall Info There is a lot of information on the sidewall of a tire. Light Truck tires are sometimes marked with an LT for "Light Truck" before the size, passenger tires are often marked with the letter P for "Passenger" before the size. Passenger tires of the same size with or without the P are virtually interchangable.Tire Dimensions Sizing example...185/60R14Tire Diameter (and sidewall height) calculation: 185mm (width) x .60 (aspect ratio) = 111mm (sidewall height) x 2 (because there's a sidewall on top and bottom) = 222mm (both sidewalls) + 355.6mm (rim diameter 14" converted to mm) = 577.6mm or 22.74" (tire diameter)The first number is the width of the tire in millimeters, measured from sidewall to sidewall. To convert to inches, divide by 25.4 In the example above, the width is 185mm or 7.28".The second number is the aspect ratio. This is a ratio of sidewall height to width. In the example above, the tire is 7.28" wide, multiply that by the aspect ratio to find the height of one sidewall. In this case, 185x0.60=111mm or 7.28"x0.60=4.36".The last number is the diameter of the wheel in inches.To figure the outside diameter of a tire, take the sidewall height and multiply by 2,(remember that the diameter is made up of 2 sidewalls, the one above the wheel, and the one below the wheel) and add the diameter of the wheel to get your answer.One flat. Change all four?Whenever there's a significant difference in the outer diameter of of one tire in a set of four, it adds to the work that the differentials have to do to compensate for that difference. The axle differential would get a workout equalizing the right and left tires, and the center differential would get a workout equalizing the front and rear. In part-time 4wd trucks, however, there usually is no center differential to cover the difference so accelerated tire wear can be expected when tire outer diameters differ (when in 4wd mode).This issue arises in long-term use, as differentials are always compensating for different tire rotations, especially in corners. They're designed to work. With an odd sized tire, though, the diffs are working in straightaways as well. Bottom line, the added stress shortens the life of the differentials.The problem is compounded in cars with a limited slip type of differential because there's a friction component to decrease the differential's natural desire to send power to the tire with the least traction.As far as affecting handling, the truck might pull if you put the tire on the front. There's also a difference in traction between new tires and old, which can change the understeer/oversteer balance built into the truck.Speed RatingsIt 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.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.N = 87 MPH = 140km/h (spare tires)P = 93 MPH = 150km/hQ = 99 MPH = 160km/h, (winter/light truck tires)R = 106 MPH = 170km/hS = 112 MPH = 180km/hT = 118 MPH = 190km/hU = 124 MPH = 200km/hH = 130 MPH = 210km/hV = 149 MPH = 240km/hZ = 149+ MPH = 240+km/h*W = 168 MPH = 270km/hY = 186 MPH = 300km/h*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 the Z rating to identify the tire's speed limit. In a nutshell, the W and Y ratings indicate how fast a Z rated tire can be driven.So, W and Y rated tires are considered "Z rated," and "Z rated" tires have an actual speed limit indicated by either a W or Y rating; listed in the service description (eg. 97W, 89Y, 91H, etc.).

[gingerracer]

thanks for that info. it was very ignorant of me not to know that tires have their own set of speed ratings.

[Bikerscum]

Great info, thanks.Why would you want Pulse Star plugs? Just curious

[Raven]

Another thread revived from the past 2003. Good one though.+1 on the (removed) Pulse Star Plugs.

[jake75]

One of the two testimonials claimed an increase from 19 mpg to 23 mpg.I am a skeptic - if a spark plug actually could increase gas mileage - even by 1 mpg - I am sure that auto companies would be using them. The $25 cost per plug would probably be $3 if you were buying 500,000 of them.The FTC rule says that you can't make a claim via a testimonial unless that claim is true, but there is so much fraud in the US that the FTC can only scratch the surface.

[Bikerscum]

The Great Plug Debate has been around since Splitfires first hit the market years ago. Do they work? No. And yes. My understanding is that it all comes down to how good/bad your ignition system is in the first place. All cars misfire a certain percentage of the time. If it's 2%, cutting that in half is not going to make a noticable difference. If it's 20%, a big gain could be made. Chances are, people that swear by them, & those that swear at them, might both be right. But the plug is just a band aid for what's causing the problem in the first place.