Wheel width/offset choice for 80 ??

[T Y L E R]

Hi , I was reviewing another thread on backspacing when something IdahoDoug made me pause ..

For example, the backspacing of an 8" wide wheel with zero offset is 4 inches. Now slap on a 10" wheel some shop has talked you into because it has "stock" backspacing of 4 inches. But what's happened to the key number - offset? Well, offset went from zero to a whopping 2 inches, which dramatically impacts steering, etc. The biggest thing you'll notice with offset changes are that the truck will want to follow cracks in the road, wander over bumps, and not steer well in hard braking.

I am considering IROK 36X13.5 radials . After reading this I went back to the Interco site to check if they came in that size for a 17" wheel . They do .. a 17X9 .

So I have a choice ...

36X13.5R16 on 16x10 4.0" BS 2" offset
36X13.5R17 on 17x9 4.5" BS 0" offset

Sometimes I hate choices ..

With the equip listed in my sig , can someone with some experience gauge how each setup will fare ? Can I safely assume the 17x9 will cause less wandering .. but with a 1/2 more tire medially will that cause rubbing issues more so than the 16x10's ?

Ramble on .. I'm all ears .

Tyler

PS : Keep in mind I'll be adding at 'least' 2" lowered bumpstops Fr and Rr before I begin flexing this thing up .

 

[T Y L E R]

What a jackass ... I thought it was a typo for some reason on the 4wheelparts , but it's not . The wheel I spoke of in the 17x9 is only 6 on 4.5 ..


The science in the question still stands though .. perhaps we could just speak in generalities . Is it best to strive towards a zero offset wheel (as we widen our wheel choices) , even if more wheel and tire are being stuffed medially ?


TY

 

[Gold Finger]

If the amount of medial increase in tyre wheel, is balanced by a similar amount of lateral deviation then surly equilibrium would be achieved. Not withstanding that wider tyres tend to squirm any way.

 

[T Y L E R]

*huge erase...*

Starting again ..

If 0 offset is optimal , then 'why' is it optimal . Great it has the same offset as stock , but it could also be presenting more width into the wheel well as I go to a wider wheel/tire combo .

As I do widen my wheel/tire combo , how will it manifest itself in general in terms of rubbing ? Both in flat-ground turns , as well as flexing it up on rocks ?

Positive offsets will leave more tire laterally ... what will that effect ?

On a 10" wheel , a smaller offset (approaching 0) will present more tire medially . What will 'that' effect ?



TY

 

[landtank]

I don't understand the focus on offset. What's critical is the backspacing/ rim width comparison.

for example:

16 x 8 rim with 4" backspacing means the center of the tire is right at the hub where the rim bolts to

16 x 10 rim with a 4" backspacing means the center of the rim is 1" to the outside of where the rim bolts to the hub. A 10" rim would have to have 5" backspacing to be centered.

When you set up an axle you have to determine where the center of the tire/rim is so when the wheel is turned the center of the tire pivots in a determined fashion.

At this point I'm unaware of any 10" rim that has the proper backspacing to maintain designed centering of the wheel.

The above was an example only and doesn't reflect actually 80 series numbers.

 

[T Y L E R]

Agreed Rick ...

16x10 .. 5" BS = 0 offset ... almost , but not always .

Lets ignore that issue for now , as the two almost always balance out ..


Look at how the 16x10 4" BS will ride and function .


I need to get off to bed now , when I wake I'll PM all the guys I can think of that are running 10" wheels on an 80 , and see what these drivers actually experience in various driving conditions .

 

[Junk]

with all the problems folks have had with swamper radials, why choose them t?

 

[hoser]

Just to correct things, an 8" width wheel is actually 9" wide with the flanges included. In order to have "zero offset," a 16x8" wheel will have 4.5" backspacing (9"/2) and a 10" wheel will have 5.5" backspacing.

Backspacing measurements are commonly used for trucks because owners are concerned with inboard clearance. Racers like to measure things in offset because they are more concerned with handling. But, yes, they measure they same thing.

Zero offset is not always optimal but that is the spec to which the Toyota engineers designed FZJ80 steering system.

Tyler, ideally, your new 10" wheels will be the same offset as stock but this might cause interference problems on the inner side of the wheel. Also, ideally, you'd increase your axle width to gain stability with you new lift. But, that's not going to happen w/o big bucks (and added steering issues). So, changing your offset a little bit can make good economic sense.

IMO, it is okay to stray away from the OEM spec a little bit and go with wheels that are slightly negative offset (-25.4mm or less). You'll get a little more steering effort, very slightly more wandering on the freeway, slightly more tire scrub when turning. But on the upside, you'll get an increase track width for better stability on/off road which is safer for a lifted truck.

A 10" wheel with 4.5" backspacing would have a -25.4mm (-1") offset.

Does that help any?

 

[T Y L E R]

Good reply , thanx .

Unfortunately the wheel I'm trying to get is only listed as a 4" BS .. 16x10 . They don't list the offset . But I imagine it is outside your definition of reliable parameters .. yes ?


TY

PS : Junk .. I have looked across the web , and the IROK radials are getting good feedback so far . Mind you I'm not a member of pirate , so I haven't been able to perform a search on them over there .. though I hear guys have spoken of them .

 

[landtank]

Never realised that you include the lip as part of the equation. I just stick with factory and forget about it.

Ty, is there another reason other than looks, that is driving you to buy rims?

 

[T Y L E R]

Never realised that you include the lip as part of the equation. I just stick with factory and forget about it.

Ty, is there another reason other than looks, that is driving you to buy rims?

of course ...

1. Safety in wider track - greater stability
2. 16x10 is what 36x13.5 SS IROKs require as per spec


TY

 

[Junk]

2. 16x10 is what 36x13.5 SS IROKs require as per spec

Just keep in mind that a few of us think that is utter bullocks.

I'd expect them to wear quicker than most radials and have sidewalls that will be cut by one of the first branches you tread over. Just keep it in mind.

 

[ginericLC]

First, I'd take the idea of getting IROKS for an 80 and toss it right out the window. Get the TSL Radials if you want a big agressive tire. Granted I live in Idaho and there aren't probably 35 trucks running Iroks in the whole state. The ones I have seen have worn out when daily driving them.

I run 15x8 wheels on my 80 with 3.25" backspacing. It makes the rig quite a bit wider. I'm only running 35" BFG MTs but I have no rubbing and I'm running Js with no spacers.

I'd run 16x10s with 4.00" backspacing. I wouldn't worry about it.

I've found some 17x9 steel wheels that I like that are 4.25" backspacing. That is what I've decided I will probably go to next.

 

[hoser]

Unfortunately the wheel I'm trying to get is only listed as a 4" BS .. 16x10 . They don't list the offset . But I imagine it is outside your definition of reliable parameters .. yes ?

Go for it! I'm sure there's somebody else around here running that offset.
But I also forgot to mention that you will feel more steering wheel "kickback" when using negative offset wheels. So, if you don't have a steering stabilizer now, you'll probably want one.

The wheel you are proposing has a -38mm offset. If you want to see what that feels like before you buy them, you can put some 1.5" wheel spacers on your stock wheels. That will also give you a -38mm offset. Heck, you might not even be able to tell a difference.

 

[lc1996]

Tyler, here's a little of my experience w/ 16x10s on 35" MTRs. The only rubbing I experience is a little when the wheels are turned and the 80 is moving on an off camber path. For example, when backing out of my driveway onto the street. I think it's only when wheels are slightly turned when the rub, I'll have to verify that tomorrow with some pics. Oh, and yes these are the rock crawlers made by Tech1 which has 4" bs. Here are a few pics in off camber situations to give you an idea when the rear and front are getting close to being tucked. Keep in mind I have the drop down blocks for the bumpstops from Slee's 6" Kit. Hope this helps.

Carl

 

[lc1996]

Well, here's a pic at full crank. I guess what you can do Tyler is make a guess-timate on your current setup with wheel crank to one side to see how much clearance you currently have from tire to lower wheelwell to see whether you want to go with the larger tire/wheel setup.

Carl

 

[T Y L E R]

Thanx for the input lc1996 . That last pic used to definately be my trucks weak link . I haven't check that out since the lift upgrade . When I get into the truck next , I will .

The front of the truck went up 2" or so , but by going with the castor plates instead of new control arms , I wonder if my front axle has arched down and 'back' towards the rear of the truck .... closer to the back of the front wheel well .

We'll see ....


TY