Tires too BIG !!

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Sep 29, 2012 | 01:23 AM

#16

old_dan

Fleet Mechanic

Joined: Aug 2010

Posts: 1,994

Likes: 3

From: Morgan Hill, CA

Quote:

Originally Posted by topmoo

ssj7kids, From what I understand Offset is how far from the center of the rim that the wheel bolts to the rotor/drum. Negative and positive depending on which side of center it is on. Don't even ask me which way is negative and which way is positive. I agree, the only measurement that matters is the backspacing. You can actually order wheels from some manufactures with the backspace that you want - US Wheels will do it for you, but they told me that they would only do it and ship them with no finish on the wheels.
With my TCI MII front end I needed more backspace, the most I could find on a 7" wide rim was 3 1/2" so I went with a smaller tire on the front then the back - all four rims are the same, just different size tires. Because of the large backspace I ended up putting 1 1/2 spacers on the back wheels to fit right. So, as I posted earlier, my fronts are 205/65R16 and the backs are 235/75R16. The fronts are 25" diameter and the backs are 29.5" diameter.

Charlie posted this link earlier in this thread: https://www.rsracing.com/tech-wheel.html

I used this as a reference when I ordered my wheels from US Wheel. I had been spending a little too much on the truck, so I went for some low cost steel wheels. The 5 on 5.5 bolt patten used on F1 trucks is also used on older Jeeps, so there are a lot of wheel options out there. I went for zero offset wheels.

Backspacing and offset are related. Backspace is the distance from the edge of the wheel to the bolting surface....offset is how far off center that is.

zero offset wheels are dead centered on the surface of your hub (the flat part of the brake drum or disk). Positive offset moves the center of the wheel out, so the tire would ride inboard more. Keep in mind that a wheel width is where the bead of the tire goes....so a 7" wheel is really 8" wide, and...a 15x7 wheel with 4 inches of backspace is dead nuts centered (zero offset).

I did talk to a tech rep at US Wheel. If you want offset, you can order wheels & they'll add offset for an added $5.00 per wheel....so those $85 steel wheels could go up to $90 & take a couple of weeks to get.

Before you go buying wheels with a bunch of offset, read the tech article and measure measure measure. You don't want your expensive tires rubbing on the frame when you turn...nor do you want them rubbing on the fenders.

Mine has been working out with the narrower P215 tires and spring spacers to raise it back up a little. I did note earlier that I wanted the lower control arms level. If you jack the springs way up and have the lower control arms down more than a few degrees, you'll end up with bump steer. That happens when that control arm swings through an arc...the tie rods hold their position, but the arm swings out which results in a steering input...one that you didn't turn the steering wheel for.

Dan