Hi
I’m selling some tires on Kijiji, and I’m afraid I have to admit I haven’t ever done this before. I know the condition, age and size of the rims, and the condition of the tires. However, a potential buyer has asked me what the size/type of the tires are.
Does anyone know how I measure this? and this is the number on the tires: 205/50R17 89V
If you could also explain what the number means that would be great for future reference.
5 Answers

The first thing your size will start with is a letter. This letter is typically a P which stands for passenger tire.
Next will be a number which represents the width of the tire in millimeters. An example of this is 205.
The second number of the tire size represents the ratio of height to width (aspect ratio). This will be a number 50 – 70 (in your case 50) for a typical passenger car.
You will have a letter seperating the numbers which is usually an R which stand for Radial
The number after the R in the previous step shows your diameter of wheel in inches. This number will vary from 1322 (17 in your case). Basically its the size of your rims for the tire

205 is the “Section Width” of the tire in millimeters (measured from outer sidewall to outer sidewall NOT at the tread.
50 is the “Aspect Ratio” or the measure of the height of the tire from the bead to the top of the tread taken as a percentage of the Section Width. In simple terms the sidewall is 50% of 205 mm.
R means “Radial” construction
17 is the diameter of the wheel the tire is mounted on in inches.
89V is the “Service Index” which gives the tires Load Capacity (the 89) and Speed Rating (the V).
Anyone looking for the tire should have a reasonable idea what they need so it isn’t that important that you know what any of this means. This tire size is most commonly found on Mazda 3’s, BMW 3series and some Saab’s and Volvo’s.

205 50 R17

ok it’s simple: 205mm from bead to bead (bead= what the rim touches) 50% of the 205mm is in sidewall height. and that is mounted on a 17″ diameter wheel. 89 is the load indexing of the tire:= how much weight the tire can carry. V = the speed rating of the tire. V should be up to, no more than 148 MPH. tire height is calculated by 205 divided 25.4 times 2 plus 17 = 33.14″ tall

Tell the buyer that the size is 205/50R17 and then he is looking for a type… Like all season, slicks, snow etc.
Excellent explanation of numbers here: http://www.ehow.com/about_5394024_tiresizeexplan…
Google ‘tire size explanation’ for more