What do each of the numbers on the side of the tire mean, me and my cousin were trying to figure it out tonight, for example, 270/45/zr17 what does the 270 and the 45 stand for, i know what the zr17 stands for.

 

270 is the tire width, 45 is the sidewall hieght

 

ok so on the sidewall height is the bigger the number the lower the profile or smaller the number the lower the profile

 

smaller the number smaller the profile

 

So im safe putting 270/45/zr17 on back and 245/45/zr17 on the back of my 87 gt then right

 

No,
The first number is the tire width in millimeters
However the second number is the sidewall aspect ratio compared to the width. Its is not uniform. So 45 does not = 45 if the first number (width) is not the same.

 

The 45 means that the tire sidewall height is 45% of its section width. So 45% of 270mm is not the same as 45% of 245mm. This means your tires will have different sidewall heights, which means they are not the same size.

 

Get a 275/40 and 245/45 if you want the same sidewall height but wider rears. 275/40/17 is normal for a 17x9" wheel. 245/45 is normal for a 17x8" wheel.

 

Well i have 245/45/r/17 all the way around right now i just want when i put the wider tires on the back to look alright with the front cause obviously the front wont be as wide

 

I like this idea but doesn't really allow for rotation does it? It would seem really stupid to rotate so that the wider tires are on the front and the skinnier are on the back. How do you solve this problem?