jfoltz

I have a stock 91 toyota pickup and i ordered some super swamper tsl sx 31x13.50x15 tires and some jegs d style steel wheels 15x10 with a 4 inch backspace. Will this backspace work or do i need less backspace?

arlindsay1992

iTrader: (8)

Stock backspacing is 3.75". On my 87 4Runner with 31x10.5x15 tires, stock wheels, and BJ spacers I have less than 1/4" of space between the tire and upper control arm at full droop. If you have stock suspension, you might be okay.

bruzer

4" back spacing and 13.5 wide tires will most likely rub. I could be wrong though.

arlindsay1992

iTrader: (8)

Well he's using 10" wide rims. It's questionable.

93Xtra-Cab

I have 32x11.5 tires on 15x10 rims with a 4" backspacing. They still rub a bit when turning, even with a 1.5" lift. The 31" tall TSL SXs are probably the same height as my all terrains and have a wider tread width. So they will definitely rub. More backspacing would probably be better, however I don't know how much.

MudHippy

More as in less you mean.

arlindsay1992

iTrader: (8)

Well, too little backspacing with a wide tire will make the outside edge of the tire rub on the inside of the fender when you turn.

MudHippy

I don't have any real experience with the exact setup he's doing. I can say this however. On my 88 I've ran 33x12.5 on 15x10 3.5" BS with the t-bars cranked(~1.5") and had NO RUB at all. Same setup with 35x12.5s rubs a little bit, when the suspension is fully compressed and the wheels are turned all the way to lock. Even with the pinch welds hammered back.

EDIT: Crap! Forgetting about my 3" body lift. So, nevermind. I don't know what I'm talking about. See even I say stupid things sometimes. Feel better now? Wait...35 - 3 = 32. So...yeah. He's cutting it pretty close. I'll have to agree with you on that then.

MudHippy

I've been mulling this over. And I've come to some conclusions. Or, rather, opinions. Based on logic, and sound reasoning. Nobody take offense to what I'm going to say now. I'm trying to debunk an internet myth here, if I can. So you might get a little ticked at being wrong. But that's really not my fault...is it?
Right. Because the clearance there is going to be quite a bit lower with BJ spacers installed.
You know, I've always heard that. And I guess the reason it kinda made sense to me was because I've always ran 15x10 wheels with 3.5" BS on my 88. And, like I said, with 35x12.5s they've always rubbed. So I figured that had something to do with it(if not just because I don't have enough lift to fully clear them). But I'm not really seeing how backspacing has that much to do with it now. It seems to me to be based almost entirely on tire diameter(like I said, 33s same width = no rub). I can say with a high degree of certainty that 35x12.5s on 15x10s would rub on the fenders no matter what the BS was(within reason). And any more than 3.5" would almost certainly rub on the idler arm, and probably the pitman arm(or steering gear box) as well. The clearance there is fairly minimal when turned to full lock. But, so far as I can tell, no reasonable amount of backspacing would cause a clearance with the control arms(plenty of room there).

So, I'm retracting my previous statement. I can't really see your point there. It just doesn't make a whole lot of sense to me. I can see the line of reasoning involved in drawing that conclusion. But I can almost guarantee you it's flawed(to some extent). That is, until I can gather enough physical evidence proving it to be. I know what you're thinking, and why. The question is, do you know what I'm thinking, and why? If not, it might matter a little, but not as much as tire diameter. And there's other places where they can rub too.
Well:

1. The 31x13.5-15LT TSL SXs are 30.8" in diameter. So I highly doubt they're the same height as your 32s.http://www.intercotire.com/tires.php?id=15&g=1

2. Your 1.5" BJ spacer lift isn't going to gain you any added tire clearance over stock. Unless you added 1.5" to the LCA bumpstops. So that the compression travel was 1.5" less. IOW those size tires on your truck probably rub because you have(essentially) no lift. And BJ spacers would lower the amount of tire clearance from the UCAs, no matter what you did.

3. Like I'm getting at here, backspacing doesn't really have anything to do with it(or if so, very little atleast). So far as rubbing on the fenders is concerned. And more backspacing is going to put you closer to rubbing on other things(named above).

4. Based on my observations(see below), I can't see 31s of any width(readily available), on any rim with any reasonable amount of backspacing, rubbing on anything. Even on a stock truck. And if they did, it would(probably) be because there was too much backspacing(not too little).

You might be right(though I believe the chances are negligible that you are). BUT, and this is the part I've been waiting to get to here, so get ready. I have a 90 PU I recently purchased as a fixer upper. It has what appear to be 15x8s w/ 31x10.5s and ~4" backspacing. And they nowhere near rub on anything. And since backspacing is going to be the same regardless of how wide the rims are, if they were on 15x10s w/ ~4" backspacing it would be no different. They'd just stick out 2" more(the rims, not the tires). Which, so far as I can tell, wouldn't matter at all(rub wise). And from what I can see on my 90 truck, if the tires were 3" wider(with the same ~4" backspacing on whatever width rims), that would still leave PLENTY enough clearance space(and cause no rub). This is on my basically stock(no lift) truck atleast.

So, maybe I'm right, maybe I'm wrong. But that's where I stand on it. And I'm not budging, without good reason to. Sorry, to all, if I ruffled your feathers. I really had to get that off my chest though. Now on to other troublesome matters...