Tire sizes.

[39mto39g]

Did you ever wonder what those numbers ment on the side of your tires? R245-45-17Z.

Here is a little help in understanding those numbers

Example:

225/40R18

225 ? Section Width in mm (Section Width or Tire Width is the measurement of the tire from sidewall to sidewall)

40 ? Section Height/Aspect Ratio (Aspect Ratio is the ratio of the height of the tire?s cross-section to its width. In this example, 40 means that the height is equal to 65% of the tire?s width. This is also sometimes referred to as ?Series?.)

R ? Construction (The "R" stands for radial, which means that the body ply cords, which are layers of fabric that make up the body of the tire, run radially across the tire from bead to bead. A "B" indicates the tire is of bias construction, meaning that the body ply cords run diagonally across the tire from bead to bead, with the ply layers alternating in direction to reinforce one another. Newer tires also have new sport constructions, such as Z. See your preferred tire manufacturer?s website for details.)

18 ? Wheel Diameter (18? diameter)

Sometimes your tire will have a letter in front of this information indicating ?P? for passenger car or ?LT? for light truck.

There are a lot more numbers on the side of the tire, Like traction letter and wear letter, If you like I'll go into those also.

Ron

[PHO127]

As a racer you seem to be up on the latest and hottest. A couple of tire places here in Atlanta are advertising to come in and get tires filled with nitrogen instead of air. Seems the only advantage is less heat expansion. Whasup

[39mto39g]

Nitrogin will expands less than air with heat , which means if you put 30lbs in your tire then you'll have 30lbs longer than if it was air. On a passenger car or truck, this isn't a big deal, on vehicles that have a big range in tempreture change, like long hall truckers or vehicles in Alaska, this will make a difference. I wouldn't bother.

Ron

[PHO127]

Just what I thought.

[Boats]

One thing about tires I didn't know was just how much air pressure is in a dragster? 6.5 lbs thats it. I was amazed.

[39mto39g]

Depends on the dragster and what year your talking about . Last year NHRA mandated 6 LBs , This year There is no rule that I know of, The AA/fuel dragsters and funny cars run as low a 3lbs. Lower air pressure makes there tires grow taller which is the same as a high gear ratio, NHRA has rules for RPM limit and gear ratio so its a way to get a higher gear ratio without haveing a higher gear ratio. If NHRA didn't restrict the fuel cars they would be going 3 sec by now at close to 400 mph, way to fast for most tracks,.
When I used to race my old Mach one, the rules limted my class to a 7inch wide slick. I ran 3-4 lbs in it all the time. was a hand full going around corners.

Ron

[Jerry D]

Another benifit of Nitogen over plain Air is, the lack of Moisture in the tire means less corrosion inside the tire rim(bead) and valve.

[MarineAO]

Another bennie is the molecules of nitrogen are larger and less likely that the tire will loose pressure over time.