Tires: Tire sizes, 3000gt vr4, tirerack com

Question
Tire sizes 245/45 ZR17  95W M&S Michelin are on the front of a used all wheel drive car we bought and the back has 215/45 R17 87H M&S Capitol tires.
Are these tires different Diameter?  What does the 245 and 215 stand for?  What does the 45 stand for? I assume the 17 means 17"inside.  Not sure about the 95W and 87H.
The car a 3000GT VR4 seems to drag the back tires when going up to speed.
Would welcome any assistance to these questions.
Thanks

Answer
John,

First, here's some links that explains what the numbers and symbols mean in a tire size:

http://www.tirerack.com/tires/tiretech/general/size.jsp

http://www.tirerack.com/tires/tiretech/general/speed.jsp

Here's a link that can be used to calculate the tire diameter:

http://www.1010tires.com/TireSizeCalculator.asp

If you've done the calculations, you'll find your front tires are about 4% bigger in diameter than your rear tires.  In practically all AWD cars, this is bad and can lead to failure in the drivetrain, the center differential especially.

Further, it's always recommended that AWD vehicles have tires that are of the same size, (which they aren't), the same speed rating, (which they aren't), and the same manufacturer and pattern (which they aren't).

My book says your vehicle came with 245/45ZR17's, so the rear tires do not have enough load carrying capacity.

This needs to be corrected ASAP!!  Hopefully it is not too late.

Hope this helps.