Question about wheel spacers on stock wheels

I have some used black 1.25" Spidertrax spacers I took off my 4Runner when I sold it. Just taking up space in my garage. If you want them I'll make you a great deal. Just PM me.

 

I have spidertrax 1.25 spacers and the insides of two sets of tires wore down to the cords. I never rotated my tires either though so that might have made it worse.

 

Are the front tires primarily affected?
When you increase positive scrub, the tires toe-out more, especially under braking and hard acceleration.
Are you running 0 toe?
Should be more like +.07 minimum, for 1.25" of added scrub.

 

I didn't adjust the toe only added the spacers. It's just the front tires the rear wear normally.

 

A toe-in alignment would help that tire wear.

 

haha Why is my brain telling me this isn't English? Is scrub the same as offset? Would you have to make the same adjustment with different wheels?

 

You asked for it...

Scrub radius...
Viewed from the front, imagine a line from the upper ballpoint to the lower ball joint and continue it all the way to the ground. This is known as steering axis inclination(SAI). It is one of the angles which the spindles rotate about; around +12 degrees. The other being caster...

Where the line intersects the tire at ground level determines the scrub radius. If it intersects inboard of center it has positive scrub; outboard is negative scrub. Our trucks have postive scrub, maybe 1/8" to 1/4".When you move the wheel out, through offset or wheel spacers, you increase positive scrub. A 1.25" spacer increases positive scrub length by about 250%...ETA- if no change in tire diameter. Increasing tire diameter, lessens positive scrub; about 1/4" for every 2" of wheel diameter increase.

Why's this matter...
There is now more tire outboard of the SAI. This creates a greater lever on the outboard side of the tire, causing it to toe-out more under dynamic conditions(acceleration, braking and cruise).

An alignment is a static measurement...
Scrub creates a dynamic force...
Factory spec is approximately, on average.
Caster +2.25
Camber +0.5
Toe +0.05
Toyota compensates for the small bit of positive scrub with a small bit of toe-in; as they also do with camber. As dynamic forces act on the tires and slop in components, the tires are pulled outward around the SAI and caster angles, the toe and camber zero out...ideally.

So, yes, depending on how much more you increase scrub, determines how much more you should increase toe-in.

 

no though spacers push tires out increasing scrub radius. Scrub radius is the intersection of 2 lines. Looking at the front of the truck, one line is the imaginary line drawn from the top ball joint out to the bottom ball joint like this “/“ on the passenger side and this “\” on the drivers side. The other line is a straight line through the CENTER of the tire. Where those 2 line intersect on the ground is scrub radius. If they intersect below the road that is positive scrub radius. If they intersect above the road that is negative scrub radius. Each has a different affects on individual vehicles and manufacturers build their suspensions accordingly.

 

better explanation then mine. Very nice.

 

I was able to buy my 16” with a -16 offset which gave a nice little poke out. I should get some bigger flares though. I get mud fling with the offset and 285’s

 

Thanks.
I think your description of where the 'two lines intersect'(above or below ground level) is more on point though. I skipped that step in my description...

 

Been loving my spidertrax OP

 

That's a great explanation. But wouldn't that mean that low offset wheels would have the same effect?

 

You should use these or ones like this at least up front.

 

@splitbolt answers this perfectly.

https://www.tacomaworld.com/threads...ter-wheel-offset-change.756892/#post-26976033

 

Okay that makes sense. Getting an alignment after new wheels or spacers is new to me but I understand now. I thought you were saying that's only the case with spacers and not wheels with a different offset which doesn't make sense to me lol

 

Why do you say at least up front? And would those not come with the spacers?

 

Unless they made a change, front studs have less stickout. I don't know what you bought, these lug nuts use the collar to give your more engagement.

 

Dude, this is a great explanation, I understood everything. Thanks! I'm surprised at how complex the geometry is for alignment. But this also raises a ton of questions. I guess I have to trust the tire shop that just replaced my wheels and tires (less offset and 2" more diameter) made the right adjustments.

 

Just keep an eye on inside tire wear...
What offset?

Just keep an eye on inside tire wear.