4x4 megacab CTD. no lift and no lift in future.

going from 17" to 18" wheels just because. I have available to choose from 4.5 and 5.7 back spacing. it's my understanding from reading around here that the 4.5 is for lift kits that have parts that need more clearance...and the 5.7 is more for a stock fender alignment look, which is what I'm after. I don't want the wheels to stick out.

I'm probably going to put 295/70x18 Terra Graps on these and from what I have read they will fit with stock style alignments.

any info would be greatly appreciated. Thanks.

-E

 

You are correct, less backspacing means wider stance or basically the wheels stick out farther. So in your case, where you want them tucked under wheel well, you would go for the greater backspacing. Also, be aware that offset plays a part in this as well. A negative backspace widens the stance whereas a positive one keeps it narrower...

 

thanks for your quick response and I get what you're saying but aren't we using two different ways of measuring to indicate the same thing? for instance the wheels I am looking at offer -12mm offset 4.5" backspacing or +18mm offset 5.7" back spacing. if you consider the total difference in offset of 30mm (1.2") and apply that to either of backspacing #s positively or negatively you get the other back spacing #. 4.5" + 1.2" = 5.7"

seems to me that yes offset is a factor but in the same quantitative dimension as back spacing in this particular instance. to me if you measure backspacing it is what it is.

-E

 

In your example yes. I was basically referring to if you had wheels with the identical backspacing, offset would play into how far they stuck out of stayed under the wheel well.
I've seen wheels with the identical backspacing offered in a negative, positive and no offset versions.

 

Just to clear things up, backspacing is simply the distance from the wheel mounting surface to the inner edge of the wheel. Offset is the distance the wheel mounting surface is from the center of the wheel, which can be a positive number or negative depending which side it is on.

As long as your new wheel is the same width and backspacing as your stock ones then it will sit in the wheel well the same.

 

The only way that is possible is if the wheels were different widths.

 

How to Measure Wheel BackSpace

 

Thanks for the info guys. This is all confirming what I have read and learned.

Does anyone happen to know what the stock offset or backspacing is on the 17" plastic chrome steel wheels? Otherwise I'll pull one and measure it.

Thanks again.

-E

 

Not off hand, but there is a set I can measure over at my old mans. I will check today while at work. I am pretty sure they are 8" wide and somewhere around 5.5" of backspacing.

 

yeah that's prob right from what I have been reading...be lot easier for me to jerk one and measure than for you to go somewhere. thanks for the offer though.

-E