What Is The Maximum Frame Width For A 225/75R15 Tire Size On A 3,500lb Axle With A 95" Hub Face

Updated 01/21/2025 | Published 01/09/2025

Question:

On a 95inch hub face, 3500, 4inch axle, what is the maximum outside frame width before tire rub becomes a concern? 225/75/15 tire and wheels.

asked by: Bill

Expert Reply:

Hey Bill,

A 225/75R15 tire would have a 9.25" width and you need to have a minimum of 1" between the tire and frame so we'll add the two together for a 10.25" space needed for the tires on both sides. That being said you also have to figure in where the spring seats can sit on the axle, which can affect the frame width as well since spring seat have to sit in the middle of the frame rails.

The spring center for a 3,500lb axle with a 4" drop would need to be spaced from the hub face a minimum of 14" to a maximum of 23". Going outside of this range will throw off the leverage and likely damage the axle/spindle. Just going with the 14" minimum your frame rails would need to be centered at 67" apart.

If I made this more confusing let me know and I can explain this more.

expert reply by: Kevin C

3,500lb spring seat spacing from hub face
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Axle Dimensions Diagram
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Do 8.

1/17/2025

Do you mean centered at 87? 67 doesn’t sound right

Kevin C.

1/20/2025

@Do8 If the hub face is 95" and you have to have a 14" to 23" spacing from the center of the spring seat to the hub face then you'd just subtract that spacing from both sides of the axle to see what your frame rail spacing would be. If we go with the 14" minimum that would leave you with 67" from center to center of the spring seats/frame rails.

Bill

1/21/2025

@KevinC I think the 14 to 23 is the overall width. my understanding is , that with a 95" hub face the maximum spring centers is 14" less than 95 = 81" and the minimum width of spring centers is 95" - 23" or 72".