How to Read Your Tire!

[militarydave]

Ok everyone, for those who don't know, i've taken the liberty (and lunch hour) to put in layman's terms what the numbers/letter on the sidewall of your tires mean. this has been re-worded and taken from various sources to not violate any copyright laws and/or infringements!

I shall use my stock tires from my Crown Victoria, which are P215/70R/15's.

common tires are P and LT, which P is for passenger tire, and LT for light truck, and T for "temporary" spare tires.

the next number in the group is 215, which is the aspect ratio for the width of the tire that is measured from sidewall to sidewall in (mm).

The following number gives the sidewall height as a percentage of the width. so for mine it is 215mm for the width, and height of 70 as a % of the 215

Next comes the Letter designated in R, B, or D.
R=Radial
B=Belted Bias
D=Diagonal Bias

the next number after the letter (R 15) is the total amount of inches of you wheel size. my case: i have 15 inch wheels.

there is also a load weight max that the tire supports when cold along with a Load Index.

a letter also indicated the "Speed Rating". such as V, Z, S, which all have their maximum speed rating (if you can drive that fast)

The type of tire is also along the sidewalls, such as All Season, Mud and Snow, etc.

Some brands have tire wear indicators, that pop up automatically once the tire tread starts to go below as certain height. the tire pressure is also listed on the tire itself, if not found on the car rear door or service manual.

it is stated that "cracked" looking tires or "weather checking" is normal and not a defect of the tire. check for uneven treadwear, which is a clear indication of a much needed alignment, ball joint or other suspension notice.

Nitrogen inflation helps when in extremely hot/cold temps, but can cost upwards of $30-$50 for all 4 or 5 tires.

remember to always balance rotate your tires for maximum tire life, and constant gas mileage. hope this helps!

-dave

[mark v]

Also the PSI stated on the tire is NOT what you fill it up to, always fill it to the PSI stated on the door tag.

[militarydave]

yes. thank you for clarifying that!

-dave

[trueblue]

Dave, good job..... :thumbsu

We have been running ET Streets for several years and this year we will be "slicking up" our turbo car... anyone have any preference or suggestions on which brands they like or have used successfully? . We have every expectation of getting 900hp to 975hp to the ground.

[mark v]

Correct tire PSI drives me nuts when people use what says on the tire.

Good informative info you posted, it will stay on top of the forum.

[JoeyGowdy]

Nice thread, good info - also if you need to compare tire sizes here is a handy tool:

http://www.1010tires.com/tiresizecalculator.asp