WHats is an offset? Why do we need 45 or 48?

What does it mean if wheels 17x7.5? I know 17 is the radius of the wheel but what the heck is 7.5?

These may be stupid questions but I couldnt find them in the search.

 

FIRST OFF...there is only one kind of stupid question....those that are not ask by someone that doesn't know the answer. SO....

to answer your quesitons...

OFFSET....if you were to look at the flange where the wheel contacts the disc/drum when you mount the wheel on the car....now put that wheel in front of you and draw an imaginary line UP and DOWN from that flange through the wheel....the OFFSET...that that amount in Millimeters ( mm ) that that line is OFFSET from the exact centerline of the wheel. you can have either positive offset, negitive offset...or NO offset. WE need a 45 or 48 offset on our wheels to keep them from rubbing on the inside....to keep the correct clearance between the wheel/tire and our struts, the spring perches...and the wheel well itself.

as for the 7.5.....your wheel you are talking about is in fact 17 inches in diameter.....and its bead seat width is 7.5 inches.

 

Let me see if I get this straight. Ooffset doesnt affect the wheel itself. It just affects its mounting point. Which means you have to change the wheel mounts?

Bead seat width? Do you mean how wide the wheel is?

 

Please use the search function. Answers to most standard questions like this can be found that way. In this case you would have found a link to the best place to learn this stuff. http://www.tirerack.com/wheels/tech/wheeltech.htm