Wheel Help

[73Chally]

Sorry if this was covered in the Sticky Wheel thread, but I was not able to find the exact combo that I am looking at using.  I am going to buy a set of AR Torque Thrust II wheels for my 73 Challenger, and am a bit unsure of the backspacing that I will need.  I have gotten several different answers from Ebay sellers, and do not know who to trust.  The wheels I will get will be 17x7 for the front, and 17x8 for the rear, and I am planning on running 235/50-17 tires on the front, and 255/50-17 tires on the rear.  What size backspacing do I need?  Should it be 4-3/4" for both front and rear, or 4" on the front?  Also, does the offset matter?  I have seen 0mm, 6mm, 8mm, etc.  Thanks in advance for the help.  This is going to be my Christmas present to myself, and want to be sure I get the right setup.

P.S.  It is a stock suspension with XHD rear leafs.

[the_engineers]

Sorry if this was covered in the Sticky Wheel thread, but I was not able to find the exact combo that I am looking at using.  I am going to buy a set of AR Torque Thrust II wheels for my 73 Challenger, and am a bit unsure of the backspacing that I will need.  I have gotten several different answers from Ebay sellers, and do not know who to trust.  The wheels I will get will be 17x7 for the front, and 17x8 for the rear, and I am planning on running 235/50-17 tires on the front, and 255/50-17 tires on the rear.  What size backspacing do I need?  Should it be 4-3/4" for both front and rear, or 4" on the front?  Also, does the offset matter?  I have seen 0mm, 6mm, 8mm, etc.  Thanks in advance for the help.  This is going to be my Christmas present to myself, and want to be sure I get the right setup.

P.S.  It is a stock suspension with XHD rear leafs.

Offset and Back Spacing are two different terms used to describe very similar things.  Offset is measured from the center of the wheel and backspacing is measured from the inside lip of the wheel.  An 8" wheel with 4" of backspacing would have a 0 MM offset.

Check this link out if you want to try different combinations...http://www.rims-n-tires.com/rt_specs.jsp

[GoodysGotaCuda]

Just being curious, but why are you limiting your tires to those specific sizes? You can clear a pretty good tire all around. Those tires you are planning to put on the rear I have on the front of my stock Barracuda with 17x8" with 4.5" bs. And just a thought, but if you are going to run a 255, you can probably run equal wheels and be able to rotate them if you wanted. 6" bs on a 18x9 stuffs a 295/45/18 on my car as well.

[73Chally]

I know it's a bit different, but I like the fact that the tires I am looking at give the exact same overall dimensions of the stock 15 wheels with 235/60 front and 255/60 rear.  I want to keep a pretty much stock ride height, but I like the bigger wheels.  I'm not sold on these tires, but I will most likely stick with the 17x7 front and 17x8 rear wheels.  As a side note, though, would 235/50-17 tires fit on a 17x8 wheels, or is that too narrow of a tire to go on an 8" wheel?

[Bullitt-]

Yes per   http://customwheelsmarket.com/rimwheelwidth1.html

245/50/17 would be a closer diameter match to OE   
http://www.miata.net/garage/tirecalc.html

[GoodysGotaCuda]

I know it's a bit different, but I like the fact that the tires I am looking at give the exact same overall dimensions of the stock 15 wheels with 235/60 front and 255/60 rear.  I want to keep a pretty much stock ride height, but I like the bigger wheels.  I'm not sold on these tires, but I will most likely stick with the 17x7 front and 17x8 rear wheels.  As a side note, though, would 235/50-17 tires fit on a 17x8 wheels, or is that too narrow of a tire to go on an 8" wheel?

235s should do fine on 17x8s. Just a word of advice from one running larger wheels, having the same height as 15s and running 17s may give the wrong illusion that you are looking for. The lack of sidewall becomes very deceiving and tends to look more like rubber bands all around. Making them look larger than 17s and more like 20s if you catch my drift. However, it is definitely you're decision on the wheels.

My rears are 28.5" tall, little taller than the average 275/60/15 for comparison sake. Fills up the wells which is what I'd consider key for getting the right look with larger wheels on older cars. The 255/45s up front are 26" tall and look best with the torsion bars loosened up a tad




Good luck and enjoy what you decide, post pics!