Tire Retard: Please Educate Me!

[Brian Dieckman]

For cryin' out loud, what do all those freakin' numbers mean?

I have the stock 16" x 8" (I guess) wheels, so I should look for a 16" tire that's how wide? Is it measured in inches? obviously not, since the numbers are in the 200's.

Help me. I'm obviously retarded when it comes to this crap. I'm going to need new tires in about 5K and I don't want to get hosed.

-Brian

[firebird1]

i think i can help i have a 1999 firebird. stock tires for mine is 215/ something somethings. i had the option of 235/55/r16's

if you're just lookin to replace your tires, it should say the size on the tire itself or the inside of your driver door.

its measured in mm. if you were looking to "upgrade" to a possible option, run your car through the tire search at tirerack.com. there will be a choice of tire size if there is one for you.
hope i helped

scott

[Shadly]

I currently have 245/50R16 which are stock on Z28s. I used to have 255/50R16 which looked great, but I rubbed going into driveways.

[DominusEtDeusNatus]

The numbers are retarded. They use inches and millimeters all in the same line.


Look at your tire. Lets say it says 245/50 16

Translation: 245mm wide 50% of that is the sidewall width and its on a 16 inch rim. When you want the total height of the tire you do 245x50x2(2 sidewalls) then convert to inches and add 16(wheel).

Usuall sizes on 16x8 wheel are. 235, 245, 255 / 45 50 55. Combinations of those.


Clear enough?

[Guardsman]

245 is the width of the tire in mm

50 is the aspect ratio, which is the width times the aspect ratio as a percentage (245 x .50 (50%))
245 x .50 will give you the sidewall height of the tire in mm. So, 245 x .50= 122.5mm

Divide that number by 25 (25mm in 1 inch). That will give you the sidewall height in inches.
122.5/25= 4.9 inches

Now, you double the sidewall height, and add that to the diameter of the wheel.
16+4.9+4.9=25.8"

[Brian Dieckman]

Excelent!

So as long as I keep the same outside tire diameter, my speedo is cool, right?

Man. Why so complicated? couldn't you just say "16 inch rim, 4 inch sidewall, 8 inches wide" and leave it at that?

Anyway, thanks for the info. I'll be memmorizing this immediately.

-Brian