Tire Question from Mastiff

Mastiff

Mastiff

Member
I should be in business early next week with the mr. Scout springs, u-bolts and shocks (the kit), plus I already have the shims and 4" shackles from ihon. I'll probably need some longer brake lines, which I can get locally.

I'll have to see how the lift looks once it's on, but maybe a skinny 32" tire will fit? There are some 32x9.5x15 super swampers available:

super swamper sam-38 - interco super swamper tsl tires - overview - summitracing.com

What do you think?

I'll probably get new wheels too, what size do I want, besides 15" diameter?

Btw, I'm not sure if I'm corrupting Robert's thread with all my questions. Should we move these posts to a new thread under suspension?
 
Re: Before and After of My Scout 80 CS

mastiff said:
I should be in business early next week with the mr. Scout springs, u-bolts and shocks (the kit), plus I already have the shims and 4" shackles from ihon. I'll probably need some longer brake lines, which I can get locally.

I'll have to see how the lift looks once it's on, but maybe a skinny 32" tire will fit? There are some 32x9.5x15 super swampers available:

super swamper sam-38 - interco super swamper tsl tires - overview - summitracing.com

What do you think?

I'll probably get new wheels too, what size do I want, besides 15" diameter?

Btw, I'm not sure if I'm corrupting Robert's thread with all my questions. Should we move these posts to a new thread under suspension?
Click to expand...

Bias tires are gunna dart around....imo, if you have the stock 16" wheels a 235-85/16 is right at 31" and about 9 wide.
 
Re: Before and After of My Scout 80 CS

I just assumed they were 15" rims... There are 32x9x16 swampers too:

super swamper sam-40 - interco super swamper tsl tires - overview - summitracing.com

Much more expensive.

Are the 16" rims needed for clearance reasons or anything, or can 15's be used?

Edit: I'm realizing I don't understand how sizing works. The tires currently on the Scout are 30x9.5x15, on original rims. The rims measure about 16.5" to the visible lip. I take it you can force r15 tires onto 16" rims? And what does 16" really mean, measured where?
 
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Re: Before and After of My Scout 80 CS

Naw, you can use either. Remember back then, if you wanted more clearance................you needed bigger wheel diameters. There wasnt a whole lot of tire choices then like we have.
 
mastiff said:
Edit: I'm realizing I don't understand how sizing works. The tires currently on the Scout are 30x9.5x15, on original rims. The rims measure about 16.5" to the visible lip. I take it you can force r15 tires onto 16" rims? And what does 16" really mean, measured where?
Click to expand...

Tires are made to fit (seal) on a given size rim -- 15", 16", 16.5", 17"... Etc

the measurement is not the "outside of the rim", but the "lip" that the tire bead seals / seats against on the inside of the rim.

You cannot put the wrong size tire on the wrong rim --- bead will not seal / will fail -- causing a "blowout" (and probably an accident).

Same goes for rim width -- all the tire manufactuers have a minimum rim width / maximum rim width. Mounting a tire "out of spec (width-wise)" can also result in a "bead failure". Doubt any tire place will mount a too narrow / too wide tire because of the liability...

mastiff said:
sorry, I'm looking for the wheel specs. Like what backspacing, width and bolt pattern to look for. Based on tire options, I think I'll switch to a 15" wheel.
Click to expand...

You state that you have 30x9.5x15 tires, so you already have 15 in rims...

Scout II rims came in 7" and 8" widths -- stock 800 rims were 5.5 inch wide

backspacing is the distance from the edge of the inside edge of the rim to the center hub -- take a tire off your vehicle (or the spare) and place a straight edge across the rim (not the tire) and measure.

Imo, you should keep the backspacing close to stock... If you use a rim with "greater" back spacing; then, you run the risk of interference -- with the steering or even the tire hitting the frame. Less backspacing could have the tire sticking out beyong the fenders (technically illegal in some states) plus added stress on bearings...
 
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Re: Before and After of My Scout 80 CS

71mtnscout said:
bias tires are gunna dart around....imo, if you have the stock 16" wheels a 235-85/16 is right at 31" and about 9 wide.
Click to expand...

Sorry, I'm looking for the wheel specs. Like what backspacing, width and bolt pattern to look for. Based on tire options, I think I'll switch to a 15" wheel.
 
Re: Before and After of My Scout 80 CS

The stock Scout II 15's fit fine, 15x7 by 5x5.5, I'm not sure what the back spacing is. I've tried thwm on my 80 with 31's with no lift, and the clearence was good.

Sorry for the hijack!!
 
mastiff said:
I'll have to see how the lift looks once it's on, but maybe a skinny 32" tire will fit? There are some 32x9.5x15 super swampers available:

super swamper sam-38 - interco super swamper tsl tires - overview - summitracing.com

What do you think?
Click to expand...


The game on wheel choice is to keep the tire center in the same relitive place with respect to the steering axis of king pin or as close as reasonably possible.

As you know I have a 32x10.5x16 tires on American racing ar767. 16" diameter 8" wide with 5 on 5.5 bolt centers to fit my Scout.

I would consider the 15 x 7" wheel for the tire you listed 32x9.5x15 which would probably be fine for 99% of the trail runs you will go on. If you think you May at some time want to go to a 10.5" wide tire go with the 15x8 wheels.

I have a bit of rubbing during full lock turns with my tires at 10.5 wide so a 9.5 wide May be a better long term choice. All of the 16 wheels they list are 4.97" back spacing so I didn't have a choice but the 15" offer 4.00 about back spacing so you will have almost 1 full inch more room to prevent rubbing.

The bolt spacing and count ar uses is in a metric spec so you want the 5x 139.7mm which works out to 5x5.5

wheel nubering can be obscure to the uninitiated so I included a picture below.

American racing: official manufacturer website- custom, chrome, polished and painted wheels
 

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What are the specs on the Scout 80 factory wheels? Are they 16.5"? Backspacing? Were they really 5.5" wide?

Robert, were you sticking with American racing wheels for some reason? I've found 4" backspacing in cragar and others.
 
No 16.5 inch rims (8 lug) -- 16.5 inch rims were used on 3/4 - 1 ton pickups / t/as

16 inch rims were for 6.00 x 16 tires which were a tube-type tire in that era, I think...

Otherwise, 15 inch rims...
 
Can someone explain this? I think this is the stock rim. It had the stock hub caps in it. The tire, if you can read it, says 30x9.50r15. The rim measures 16.5" across to the exposed metal "lip". Did someone force a 15" tire onto a 16" rim, or what?

I wonder if I could put 235/85r16's onto this rim?
 

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Not what I have seen in the past for factory equipment on a Scout 80. That doesn't mean is isn't just that I have not seen one before. Do you have all 4 like this one?
 
mastiff said:
what are the specs on the Scout 80 factory wheels? Are they 16.5"? Backspacing? Were they really 5.5" wide?

Robert, were you sticking with American racing wheels for some reason? I've found 4" backspacing in cragar and others.
Click to expand...

No reason other that they were what I thought I needed from a back spacing stand point and I liked the style.
 
Rim diameters are measured bead seat-to-bead seat. You are measuring the flange/overall diameter which is meaningless. So the tire itself is a 15" radial.

Yes a 15" tire can be forced onto a one-piece 16" rim using a power mounting equipment. There would never be any reason to do so.

A 16.5" wheel has/uses an entirely different kind of bead seat profile and is suitable only for use with properly matched 16.5" truck tires. And they are available in either multi-piece versions or one-piece versions, the bead seat design between each type limit limits the availability of proper tires for each wheel design. The tire bead construction must match the wheel bead seat design.

A 16" rim which is not a two-piece design is the norm on most light trucks in the last several years and is by far the most popular current aftermarket wheel replacement size for light truck apps.

A Scout 80 could have had 16" wheels installed oem,... Or it could have had 15" wheels installed oem, whatever the dealer spec'd on the individual order. A dealer could also spec' "wheel delete" which means no wheels/tires would have been installed. A Scout 80 would never have had a 16.5 " wheel installed oem, in those days those would have been multi-piece wheels only and have had a much larger bolt circle consisting of six holes as used on the heavier-spec IH trucks in that time.

Some two wheel drive Scout 80 were supplied oem with four stud wheels, not five stud.

The rims shown in your pic are not oem wheels as supplied to IH for the Scout 80 or 800. Many vehicles used the five on five and a half lug pattern, no telling what the oem app for those wheels May have been, nor does it really matter!
 
Okay, thanks for all the input. I assumed that they were stock because they looked old and fit the factory hub caps. I guess that's pretty far from conclusive though. My take-away from this is that I need to buy new wheels when I get my new tires. I'm leaning toward the 235/85r16's with 7" wide 4" backspace wheels. I asked about them at a 4x4 shop around here and the guy assumed they were for a dually.

Robert, your post above made it sound like you wanted less backspacing than you ended up with. Do I understand right that you think you would have less interference with something like 4" backspacing?
 
The best spec to use is the offset as that is what the steering geometry and wheel bearings "care" about. Offset is also independent from wheel width so no figuring is required to compare different wheel widths.


If you look at the excelent diagram Robert kenney posted.

10060d1275345547-tire-question-mastiff-wheel-nomenclature.jpg


You can see how the offset is the difference between the center of the wheel and the mounting surface. The standard oe wheels for scouts had 0 offset, while the wider ralley wheels had a -1/4" offset. To keep the steering geometry and wheel bearing/spindle loading within the factory specs you want to stay in that range.

To clear the steering arms, brakes and springs the back spacing is important as well.

Referring to the diagram you can see that the backspacing is measured between the mounting pad and the outer most part of the flange. However the advertised wheel width is measured between the bead seat. The difference between flange width and advertised wheel width varies slightly between brands and whether the wheel is made of steel or aluminum. For the purposes of calculations you can use a nominal difference of ~1".

For your proposed 16 x 7 wheel with 4" of backspacing that works out to the original 0" offset. 7 + 1 = 8 8/2= 4" and 4 - 4 =0. So that would be perfect as far as the geometry and wheel bearing/spindle loading is concerned.

So then the question is will the 4" back spacing clear every thing. Since Robert is running wheels with ~5" of back spacing and tires that are ~1" wider overall you should have plenty of clearance.

One thing to keep in mind about the 235/85 16 is that they are intended for 3/4 and 1 ton trucks so make sure you do not get the load range e, the load range d ones will still be way overkill for even the heaviest Scout. Plus you'll typically save a couple of $$ per tire with the lower load rating.
 
Thanks for the help. The skinny ones are only available in e. I think the ones Robert has are e too, though I could be wrong. I think this is because the skinny ones are used in duallys.

I just realized that the BFG mud terrains are also available in 235/85r16 though, so I might go that route instead. I don't think those are e, but I need to double check. We don't get to be picky when trying to go skinnier than normal unfortunately.
 
eric vanburen said:
Since Robert is running wheels with ~5" of back spacing and tires that are ~1" wider overall you should have plenty of clearance.
Click to expand...

My wheels are 4" back spacing . I just reverified the front spacing and it is 4". I taped these dimensions so there is likely some error in them. For all I know they are 16x7's :out:

appears that they don't list them anymore.? I assumed they were still availible.
 
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