The backspacing measurement is very simple, but I had to ask: I was looking at this rim http://store.summitracing.com/partde...5&autoview=sku but I can only find it with 5" backspacing. Does this mean that my tire is going to be .5" closer to the truck than the stock rims?

 

No, I don't think stock rims are backspaced 5.5". I think you'll be several inches further out than stock. What's stock for a 99 anyway? I have an old stock Toyota 15x7 steel rim that has 2" backspacing. The aluminum ones I got now are 15x10 BS@6.25", they stick out quite a bit on my truck. I think the offset measurement is what really counts, different width rims have different offset even if the backspacing is the same.

 

i dunno what wheels you have but the BS on the 5 spoke wheels on the limited were 3.75" i thought. therefore a 5" BS wheel will push the rim out 1 1/4.

 

The backspacing is from the hub to the back of the rim, correct? If so than if there were 0" BS, the outside of the rim would be 8" out ; If the BS was 8", the outside of the rim would be flush with the lugs.
This would mean that going from 3.75 to 5 would make it go IN 1-1/4 inch.

Or do I have my backspacing backwards?

 

it'll stick out farther... period...

 

Ahhhhh! I asked this in the newb section because it was such a newb question. I am way more confused than before? Can someone explain how the measurement to the back of the rim being bigger can make it stick further out?

https://www.yotatech.com/forums/show...ht=backspacing

 

put a measuring tape to the inside hub of the rim perpendicular to the width and whre the rim ends is your bs umm i dunno if that makes sense but pretend the tape measure is like your axle and when you are looking at the width of the wheel where the rim end s is your BS......... yaeh you need pictures lol

 

ah ha
https://www.rsracing.com/tech-wheel.html#backspace


http://www.high-impact.net/wheels/ba...lustration.htm

 

well...I'm pretty sure the more backspacing you have, the farther in your wheel will be, but since its an 8" wheel, it changes that as well. here's a good explanation for it all, its about 3/4 of the way down the page under determining track width.


edit: beat me to it, but still, there you go.

 

This is a link to another forum, but it has pictures and everything to explain backspacing. Pictures make understanding this way easier.

http://www.mallcrawlin.com/forum/sho...ht=backspacing

Dang, I need to type faster, and not eat while typing. Well, now you have multiple links to check!

 

Yep, the direct link is:
- http://www.4crawler.com/Diesel/Tires...ningTrackWidth

For track width and backspacing explained:

 

Thanks for all the links. I had already looked at all of those, which is why I am confused by posts 2,3, and 5 saying that 5" BS will stick out further than 4.75" BS.

 

There is backspacing and then there is width of the wheel:

More backspacing than stock = wheel sits closer to the frame than stock wheel.
More width than stock = wheel sticks out farthen than stock wheel.

So if you have say a 7" wide, 4.5" backspaced stock wheel (not sure of the exact specs on the 3rd gens) and swap to an 8" wide, 5" backspaced wheel, the inside lip of the wheel will sit 1/2" closer to the frame than the stock wheel (5" - 4.5") and the outside lip of the wheel will stick out 1/2" wider than the stock wheel (8" - 7" - (5"-4.5")).

So in that case the wheel will stick in and out farther than stock.

 

That clears is up! I thought that my stock rim was 8 in wide. I didnt know it was only 7!

 

I mentioned I did not know what width or backspacing your stock rims were, I only used 7" and 4.5" as examples. On the earlier IFS trucks, 15x7 w/ 4.75" was stock. Check out your wheels and then you will know for sure:

Inside of rim with wheel dimensions:


How to measure backspacing with simple household implements: