Need HELP! Backspacing/Wheel-Tire Sizing

[Moparmann]

Hope some of you can answer this question for me...I ordered a set of 15x8, 4.5 backspacing one piece alloy Magnum wheels (see attached pix), so I could upsize to 15" tires. I plan to run a 225/R75-15 tire to maintain my stock look. I received the wheels, but to my dismay, when mounted on the front rotor, the studs don't come through the wheel! Did I screw up? As best I remember, the original Magnum wheel has a 4.5 backspace. Please advise, and Thanks for your assistance!

 

[R413]

Either the wheel is hitting the caliper, or the center of the wheel doesn’t fit over you hub. Other possibilities are it’s hitting the tie rod end or the dust shield. You tell us.

What disc brakes do you have? Original to the car or added on later? Photos of the back side of the wheel and you brake and hub would help us help you.

Sweet looking wheels!

The hub pictured below will not allow a factory magnum 500 wheel to fit. Look how much material is on the hub, it doesn’t taper down like a 60’s hub does. These are early to mid 70’s factory rotors. I forgot the exact year and car.

 

[Moparmann]

Either the wheel is hitting the caliper, or the center of the wheel doesn’t fit over you hub. Other possibilities are it’s hitting the tie rod end or the dust shield. You tell us.

What disc brakes do you have? Original to the car or added on later? Photos of the back side of the wheel and you brake and hub would help us help you.

Sweet looking wheels!

The hub pictured below will not allow a factory magnum 500 wheel to fit. Look how much material is on the hub, it doesn’t taper down like a 60’s hub does. These are early to mid 70’s factory rotors. I forgot the exact year and car.

View attachment 990150

Based upon a previous conversion experience, I utilized the disc brake set up from a Challenger, in order to retain the Magnum wheels; which by the way fit w/ no problems. I will have to trial fit it again (and on the rear as well, but the wheel didn't appear to be hitting anything, and seemed to sit flush. Other photos, including rear view of current magnum wheel. The major difference between the two is that the old one is 14 x 7 and the new one is 15 x 8. Thanks for your quick response!

 

[Moparmann]

Oops! Left off the original Magnum pix!

 

[66Satellite47]

Ford center diameter on the new wheels?

 

[Moparmann]

Ford center diameter on the new wheels?

The new wheels would also fit a Ford, but were listed as correct for Ford & Mopar.

 

[Auto Teach]

The new wheels would also fit a Ford, but were listed as correct for Ford & Mopar.

It looks like the new wheels have a thick aluminum hub on the backside of the wheel? That could be the concern.

 

[33 IMP]

If you haven't already got one, get a digital caliper from harbor fright (they're cheap) and check the hub size, and the throat of your new wheels, compared to the old magnums. I'm betting the hub of your new wheels are too small.

 

[66Satellite47]

The center mounting hubs appear to be much thicker than an OEM steel center wheel. The solution is a "mag" wheel lug nut ( if the hole diameter works), or longer studs.

 

[Moparmann]

Will check out this info and get back with you. Thanks to you all for the support!

 

[max340]

Longer studs?

 

[Moparmann]

Well, my "problem" has been solved! Not realizing that the alloy wheel base plate was much thicker than OEM steel wheels was the cause of my distress. The simple solution was a set of E-T lug nuts, no longer studs needed! They work really well, and the new wheels look "bulked up" in the wheel wells! The only downside is, I have to change the LH studs in the left rear axle to match the other three! Thanks to all of you for the help/suggestions!

 

[hunt2elk]

Well, my "problem" has been solved! Not realizing that the alloy wheel base plate was much thicker than OEM steel wheels was the cause of my distress. The simple solution was a set of E-T lug nuts, no longer studs needed! They work really well, and the new wheels look "bulked up" in the wheel wells! The only downside is, I have to change the LH studs in the left rear axle to match the other three! Thanks to all of you for the help/suggestions!

View attachment 1002836 View attachment 1002837 View attachment 1002838

I've never seen that style lug nut before. How much metal is left around the shank? Just checked on my new Crager conical drilled and there isn't much space at all between the stud and the rim hole.

 

[Moparmann]

I've never seen that style lug nut before. How much metal is left around the shank? Just checked on my new Crager conical drilled and there isn't much space at all between the stud and the rim hole.

Not sure, but apparently, there is a sufficient amount of clearance. The wheel tech told me that 8-10 turns was good for security on the stud, and I finger tightened them to 12-13 turns before bottoming out and torqueing them down. My mechanic/race car builder also recommended them as well.

 

[hunt2elk]

Really? you too. And while we are at it, lol. Thought we were all friends around here.

 

[Moparmann]

I am VERY SORRY!! I wasn't looking too closely at the emoji's and clicked on the wrong one! I do apologize!!! I want to remain friends!

 

[hunt2elk]