Hey guys I have a question on stock wheel backspace.My 48f1 ford has stock 16x4.5 rims with 3and3.25 " backspace.Went to junk yard today to convert to wide steel stock rims,my problem is the backspace on 15x7rims it is 4"is this too close and if it is what steel rim and backspace can I use?I want 255/70/15 rear and 235/70/15 front any help would be great thanks

 

Try this website...they provide some pretty good information on how to measure backspace and backspace requirements: https://www.rsracing.com/tech-wheel.html


I think you'll find that 4 inches of backspace on a 7 inch wheel is essentially centered on the mating surface.

If you're running the stock 5 on 5.5 wheel bolt pattern, be sure to check out jeep suppliers....15x7's are popular & older CJ Jeeps use the 5 on 5.5 bolt pattern.

 

Would the4" backspace clear the frame in rear?Right now I have approx 1" clearance with stock 16x4.5 rims with 225/75/16 with 5x5&1/2 bolt pattern,thanks

 

I don't know off-hand what the backspace is on the stock 4.5 inch wheels, so you should take a couple of measurements.

Put the rear of your truck on jack stands supported under the axle and take the wheel off. Use either a straight edge or a plumb bob. Drop a line to the floor from the flat surface on the brake drum where the wheel rides, and mark the floor. Drop another line from the frame or bed...whichever is closer to the wheel & mark the floor for that one as well....accruacy is important. Measure the distance between the lines.

That distance will be the maximum that you can use....well really that represents half the maximum width of whatever tire you select...the P225's are supposed to be 225 mm at the widest point. Check the tire manufacturers website to be sure, because there is a little variation.

If you don't have sufficient clearance for the tires that you want, you can consider some custom offset wheels for an inch or more. US Wheel makes a lot of steel jeep wheels in the $85 price range per wheel. They charge and extra $5 for a custom offset. Offset is having the wheel bolt flange set off from the center line of the rim. You could gain clearance to the truck frame, but the other side of the wheel/tire will stick out more. Look at that website which defines positive and negative offset.

Also...if you go the custom route, call the wheel manufacture and discuss it with them so that the wheels come out to be what you want.

Dan

 

Thanks,my stock wheel offset is 3.00 rear 3.25 front with stock 16x4.5 rims.I will try your method of using the plumb and get new measurements,thank you for your input,have a good day