Wheel offsets for 285's on stock 5th gen Trail - Page 2 - Toyota 4Runner Forum

mdogg · 11-12-2013, 09:15 AM

Quote:

Originally Posted by pelemay

Please stop me before I say something stupid: unless the alloy wheel were actually wider than the tire, then my only real rub concern is with the rubber tire, right ? So, the result of half the tire width minus the offset would be the parameter we should actually compare, isn't it ? (The width of the wheel has no actual effect, I would think, for a constant offset.)

Let us assume that the original Trail wheel has a +15mm offset (can someone please confirm this, btw ?) and the original tire is 265mm wide. I calculate that the inside face of the tire is (265mm/2) - (+15mm) = 117.5mm "inside" from the mounting pad plane.

The "new" 285mm tire mounted on a +12mm offset wheel would sit at (285mm/2) - (+12mm) = 130.5mm "inside".

The difference between those results tells me where the new tire will end up, on the UCA side: (130.5 - 117.5) = 13mm closer to the UCA. (A shortcut to this result is that the tire is 10mm wider on either side of its middle plane and the new wheel protrudes 3mm less outside.)

I think I can easily get 13mm closer to the stock UCA without hitting/rubbing anything on that side, yes ? (...then the only remaining issue would be with the outer edge of the tire, when turning/reversing/wheeling...)

Actually, I think all of this is logical and theoretically correct. However, the reality is that it's difficult to compare tires based on the nominal dimensions. As was mentioned, all 285s (or any other nominal width) are not equal. They are roughly equal, but can still vary quite a bit. Some may be taller, some may have a larger tread width, some may have a larger section width, etc.

The other problem is that the shape/size of the tread blocks at or near the shoulder may be the deciding factor for some of the possible rubbing. Generally you won't have any rubbing in the center of the tread pattern, but when turning, it's going to be the shoulder areas that have more potential to hit something when angled one way or the other.

When it comes down to it, you're trying to match a 3D wheel inside of a 3D wheel well, so it's not quite as straight forward. From what I can tell, even sticking with the exact wheel/tire/size/offset combinations, you STILL might not have the exact same experience as another member due to some small variations in suspension (could be driver/cargo weight, sagging due to age or use, etc.). When you go to a different wheel/offset AND a different tire brand/size, that just adds another variable to the matter.

It's really a situation where the most probable fitting is from following others' suggestions. But if you want something different, it MIGHT end up costing a bit more to make it work - or you might come to the conclusion that it just doesn't work and then you have to get new tires.

pelemay · 11-16-2013, 11:24 AM

Quote:

Originally Posted by harper7

[...]comparing wheel offset is useless info unless you are comparing wheels of the same width. Backspace is how you compare and if you have the offset you can find the backspace with a chart. Not sure where you came up with stock TE at +15.

Somebody please measure bs on a TE wheel and post up so we can get facts instead of assumptions . Not that hard to measure and it's definitely a 7.5" width so it's either a 4.5"or 4.75 bs making it a +6 or a +12 offset.The how to is in the wheel tech info on the link down below.
4 years now and nobody with a TE wheel has reported the actual measured back space = lame.

Thanks Harper7. I actually took a look and now realize why the backspace is so important in our case. The UCA and some tie-rod end up pretty close to the stock tire and wheel as it is, when turning. (I come from an Xterra and I do not recall having such proximity issues.)

That said, this morning I took off one wheel of my 4runner TE. There are two distinct markings on the inside of the wheel spokes: "17X7 1/2J" and "J DOT 15". I assume that means 17" dia wheel x 7.5" width, having a +15mm offset.

I then actually measured the distances from the innermost edge (UCA side) to mounting pad, and got 124 mm. I repeated the same operation for the outermost edge (curb side) to the same mouting plane, and got 92 mm.

Hence, the total actual width of the wheel is 124 + 92 = 216 mm. (That is 8.5", so that means the flanges are each about 0.5" wide.)

Assuming symmetrical flange widths, I obtain a mid-plane lying at 216 / 2 = 108 mm from either flange. My measured/calculated offset is thus (124 - 108) or (108 - 92) which is +16mm.

Conclusion, I feel pretty confident to claim that the TE wheels have a +15/+16mm offset.

pelemay · 11-26-2013, 08:10 PM

Well, after lots of reading on this forum, and thanks to the frank advice in this thread, I opted for keeping the stock wheel, but I took a chance and ordered the 285/70/17 Duratracs (studded for winter).

After harper7's front fender mod (real easy) and after removing the (useless ?) mudflaps, I get no rubbing at all in normal/city driving !

Yay !

Thanks to all

P.S. Not removing the mudflaps would have resulted in them being eaten away quite fast by the studded tires (!)

jiveflexx · 03-16-2021, 12:31 PM

Quote:

Originally Posted by Ol'Baditude

I think that in the absence of a lift or aftermarket UCA's to dial your caster in properly, you're likely going to experience some rubbing regardless. On the fender lining in the front and body mount in the rear of the wheel well . If you go from a -12mm to a +12 mm offset you're going to be moving the wheel inwards, and combined with the wider tire you're now risking rubbing on the UCA.
Not sure what the width on the new wheels is going to be, but more width on the wheel is a factor there as well.
I'd have to say the best bet considering the info you have given is to stick as close to stock offset as you can and hope there's sufficient gap between the tire and UCA.
Seems to me anyway.

Any idea on how the 285 70 r17's would do with a -12mm offset. Thinking of getting the Fuel SHOK D666's -12mm offset.

I have the 2006 oem toyota wheels on now with the 285's along with 1.5" wheel spacers.. If I remove the spacers and throw on the -12mm rims would the space outwards be about the same?

2006 4runner, 3" lift. (For what its worth, im i nstalling a Coastal offroad high clearance bumper this weekend)

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