Pearl Street Automotive offers complete tire service including new tires, mounting, and spin balancing. Whether your looking for car tires or truck tires, Pearl Street Auto is your one stop tire center in Waukesha.
A bit about tires:
Your tire size is marked on the sidewall of your tire, it will read something like this, “P205/70R15 92S”. There may be other numbers or letters but these are the critical ones that the tire shop needs to fit new tires on your car.
So what do these numbers mean?
- The “P” means the tire uses the “Passenger Metric” sizing system for cars and light trucks and complies with P-metric (for short) load and inflation tables. Some tires are “Euro-Metric. These will not have the “P” in the description and use a different load and inflation table than a P-Metric tire of the same size and service description.
- The “205” is the “section width” or the width of the tire at its widest point (not the width of the tread) in millimeters.
- The “70” is the “aspect ratio” which measures the height of the tire from the bead to the top of the tread. The number is an expression of the percentage of the aspect ratio to the section width. In this case, the aspect ratio is 70% of 205mm.
- The “R” means the tire is of radial ply construction.
- The “15” means the tire is designed to be mounted on a rim of 14-inches in diameter.
- The “92S” is the “service description”. This is perhaps the most important piece of the size description and also the most ignored. It contains two bits of information. The 92 is the “load index” and gives the tires maximum load carrying capacity. In this case 1,400 lbs. The “S” is the “speed rating” and gives the tires rated speed capability over a set period of time at a specific inflation pressure. You really don’t need to know any more than that for normal street driving.
Whether your looking for car tires or truck tires, it’s important to know that your vehicle is set up to run on a specific tire size, but changes can be made for any number of reasons without too many problems. For example, changing the P205 number will change speedometer accuracy by about 2 mph per size. Going from P205 to P195 will slow the car down, and sizing up to P215 will speed it up. Although the speedometer will not read the same, essentially your vehicle will be moving at the same rate of speed.
Changing the middle number, 70 will make your tire wider or narrower and the numbers work backwards. A 60 tire is wider than a 70 tire. This can affect your gas mileage but one number won’t be especially noticeable. If you are buying snow tires for winter then 75 is the best number for that. The tire is thin and cuts through snow to make contact with the road.
Changing the last number 15 requires you to change the rims. That number is the diameter of the rim and there really isn’t much reason to change them unless you are customizing your car or truck. Although the trend for customizing truck tires was more common, more recently people are changing the rim size on car tires so it’s important to pay attention to the rim size.
Price comes into play more than brand name. You don’t need that $250 set super sticky car tires for normal every day driving. You can do just as well on an average $125 tire. The sticky tires use softer rubber and wear out quicker. This rule is the same for any truck tires that offer a softer rubber. Be certain to determine which grade of rubber is best for the driving conditions that you will be using your tires