question about back spacing and offest

[the great him]

ok i know this has been gone over before, so flame away, some how it just never makes any sense to me. maybe it was or is because when ive seen it, at the time it did not pertain to me(didnt have aftermarket wheels so wouldnt matter for me). but im looking at buying a wheel tire 17" WHEELS RIMS XD ADDICT GLOSS BLACK W/ 295-70-17 NITTO TRAIL GRAPPLER MT TIRES | eBay , anyhow i need to know what offset and or backspacing to get. -yes im getting my lift finally -tundra 5100s with the TRD tundra coils(all new stuff), and its time i get some new tires as well. i was only gonna buy tires but this seams like a good deal, and i like the look of those wheels. im gonna keep my tundra rims for my snow tires.

any imput on back spacing and or off-set would be nice -also if you can(try to) explain it to me so i can understand it, thanks

 

[4-Ripcord]

Offset is the distance the bolt holes "mounting pad" are from the center line of the wheel.

Backspacing is similar, it is the distance from the backside edge of the wheel to the bolt holes.

Our trucks should have somewhere between 4-4.5" of backspacing.

The offset depends on the wheel width.

 

[02SE]

Backspacing is the measured distance from the wheel mounting pad, to the inboard wheel flange.

Offset refers to where the mounting pad (the part of the wheel that sits flush against the vehicle hub) is in relation to the wheel centerline.

If the wheel has negative offset, that means the wheel mounting pad is inboard from the centerline of the wheel.

Positive offset means that the mounting pad is outboard from the wheel centerline.

Here's a pic that should help.

 

[4-Ripcord]

I win.


:cheers:

 

[A.Wilson013]

Check this site out Broheim. I didn't understand until I read it.

https://www.rsracing.com/tech-wheel.html#backspace

 

[02SE]

Offset is the distance the bolt holes "mounting pad" are from the center line of the wheel.

Backspacing is similar, it is the distance from the backside edge of the wheel to the bolt holes.

Our trucks should have somewhere between 4-4.5" of backspacing.

The offset depends on the wheel width.

The offset is not effected by the wheel width. Offset is only the position of the mounting pad, in relation to the centerline of the wheel.

Example: A 6" wide wheel with the mounting pad positioned right on the centerline of the wheel, has zero offset.

A 10" wide wheel with the mounting pad positioned on the centerline of the wheel, also has zero offset.

Only the backspacing is effected by wheel width.

 

[4-Ripcord]

The offset is not effected by the wheel width. Offset is only the position of the mounting pad, in relation to the centerline of the wheel.

Example: A 6" wide wheel with the mounting pad positioned right on the centerline of the wheel, has zero offset.

A 10" wide wheel with the mounting pad positioned on the centerline of the wheel, also has zero offset.

Only the backspacing is effected by wheel width.

There is a miscommunication. Allow me to clarify.

IF you set the backspacing at say, 4" no matter what (as the OP is likely to do). Then the offset will differ depending on the width of wheel you choose to go fit in your criteria of 4" backspacing.

That is what I meant to say, I was vague.

 

[the great him]

Size 17 x 9
Offset -12, +18
Backspace 4.5", 5.71


so im gonna go with the 4.5" backspacing but i dont know what offset to get... it looks like i need a -12 offset, is this correct and will this work?

 

[brian2sun]

02SE and 4Ripcord are both correct. Basically, (in regards to tires rubbing the UCAs) the offset doesn't matter as long as the backspacing is correct. For 285s, 4.25" BS is the sweet spot. For 315s, I'm running 3 5/8" and I still rub a little on my UCAs when fully turned so I would say the perfect BSing for 315s would be 3.25-3.5".

Another note.. Offset can get really confusing because it's measured by overall rim width. The reason it's confusing is a 17x8 wheel is actually 9" wide (outside edge to outside edge). A 16x7 is actually 8" wide. In your case, a 17x9 is actually 10" wide.

My recommendation is.. don't worry about the offset unless you are trying to figure out if the wheels will clear the brake calipers. If it's just to clear the UCAs, go by BSing.

 

[the great him]

02SE and 4Ripcord are both correct. Basically, (in regards to tires rubbing the UCAs) the offset doesn't matter as long as the backspacing is correct. For 285s, 4.25" BS is the sweet spot. For 315s, I'm running 3 5/8" and I still rub a little on my UCAs when fully turned so I would say the perfect BSing for 315s would be 3.25-3.5".

Another note.. Offset can get really confusing because it's measured by overall rim width. The reason it's confusing is a 17x8 wheel is actually 9" wide (outside edge to outside edge). A 16x7 is actually 8" wide. In your case, a 17x9 is actually 10" wide.

My recommendation is.. don't worry about the offset unless you are trying to figure out if the wheels will clear the brake calipers. If it's just to clear the UCAs, go by BSing.

well sense they are 17s im not worrying about the calipers, even though i have the 231s, the UCAs on the other hand idk, if not i guess i can run some wheel spacers till i get the LR UCAs. im gonna be running a 295 tire(kinda odd ball size but oh well). -nitto tires tend to be on the "wider" side, so it might end up being like some 305s idk we will find out

 

[brian2sun]

well sense they are 17s im not worrying about the calipers, even though i have the 231s, the UCAs on the other hand idk, if not i guess i can run some wheel spacers till i get the LR UCAs. im gonna be running a 295 tire(kinda odd ball size but oh well). -nitto tires tend to be on the "wider" side, so it might end up being like some 305s idk we will find out

Even if you got A/Ts, I think you'll need to run spacers with 295s/4.5" BSing (or just get wheels with 4.25" BSing). I used to have 305s and I know you'll need about 3.75-4"BS for those.

For 16" and larger wheels, the inside diameter doesn't have anything to do with clearing the 231s. The part of the wheel that may come into contact with the calipers is the inside "face" of the wheels. If the wheel's face is too close to the mounting flange, then it will hit the outside face of the caliper. This is where offset is important. That is why the stock 16" 5-stars clear the 231s and the stock 16" split 3-spokes don't (even though the BSing is the same on the 2 different wheels).

You could always grind the calipers or the inside face of the wheels though, as long as it's close (like within 1/16 to maybe 1/8" or so). Hope that makes sense.

 

[the great him]

i think id rather run a spacer than grinding the PC off my calipers and or hacking up my wheels, although i might be able to put the wheels on a lath and have them "machined"...

 

[VA4runnerchic]

ok i know this has been gone over before, so flame away, some how it just never makes any sense to me. maybe it was or is because when ive seen it, at the time it did not pertain to me(didnt have aftermarket wheels so wouldnt matter for me). but im looking at buying a wheel tire 17" WHEELS RIMS XD ADDICT GLOSS BLACK W/ 295-70-17 NITTO TRAIL GRAPPLER MT TIRES | eBay , anyhow i need to know what offset and or backspacing to get. -yes im getting my lift finally -tundra 5100s with the TRD tundra coils(all new stuff), and its time i get some new tires as well. i was only gonna buy tires but this seams like a good deal, and i like the look of those wheels. im gonna keep my tundra rims for my snow tires.

any imput on back spacing and or off-set would be nice -also if you can(try to) explain it to me so i can understand it, thanks

HOLY **** there's actually something you dont know??!!! WOW must be a fullmoon tonight LOL

 

[the great him]

hahaha very funny, but i told you i didnt know much about backspacing and or offset, it was all greek to me, im starting to understand it a little more now but still dont fully have it. and i dont know electical all that much, i can wire stuff and do basics, but trouble shooting, not so much, i can check for power and ground, thats about it, volt meters i can kinda read.

you just ask "simple" girl questions, thats why i always know the answer to your questions :moon::hiding::lmao:

 

[Gerdo]

Something to else to think about.
A 285/75-16 on a stock wheel (~4.65"bs, 16x7), the sidewall comes real close or rubs the UCA. If you have the same tire on a wheel that is wider (same bs), the sidewall will not bulge as much and will move away from the UCA.

 

[Rc4r]

That's a sick tire and wheel package

 

[the great him]

Something to else to think about.
A 285/75-16 on a stock wheel (~4.65"bs, 16x7), the sidewall comes real close or rubs the UCA. If you have the same tire on a wheel that is wider (same bs), the sidewall will not bulge as much and will move away from the UCA.

ok so right now i have the 17x7.5 tundra wheels with a 285 70 tire, i have about a half inch or so of clearance with the that set up at the UCA, i am going to a slightly wider tire(nittos seam to run wide for their given size and the bighorns seam to run narrow(er) for their given size), i will be jumping up to a 295 70 on a 17x9 rim with 4.5 BS and a -12 offset, do you think i will be fine?

also i think from looking at the wheels, i wont have any issue with clearing the calipers, as the spokes angle up and out and are not perfectly vertical. they should clear the 231s just fine.

 

[the great him]

That's a sick tire and wheel package

what wheels are you running? are they the same ones?

 

[VA4runnerchic]

you just ask "simple" girl questions, thats why i always know the answer to your questions :moon::hiding::lmao:

:flipoff: LOL i gotta learn somehow right?!

 

[BigRogers]

So I am trying to better understand the backspacing/offset as it relates to the stock wheels and how i can compare that to a aftermarket set.

Using this for my back spacing reference http://www.toyota-4runner.org/3rd-gen-t4rs/33980-stock-oem-4runner-rim-offset-backspacing.html#post288655 it measures the backspacing of the 5-star at 4.625" (4-5/8")

So if i understand this correct that would leave a 7" wide wheel with a wheel center of 3.5".
Doing the math that would leave the 5-star wheel to have a positive offset of 1-1/8" or 28.5mm.
Now throwing the 1.25" spidertrax into the mix brings the relative backspacing to roughly 3-3/8", which leave the wheel at a -1/8" or -3mm offset.

Now taking that information and rolling it over to the wheels I want to buy:MB Wheels 72 custom rims
These are 8.5" wide, giving them a wheel center of 4.25" (4-1/4") and a -6mm (-0.24") offset.
Which would leave me with a wheel backspacing of +/-4" backspacing.

So from what i have pulled together doing this math, it seems the new wheels would not need to run the spidertrax (which is the direction i wanted to go). However i do know that with the wider wheel there may be some clearance issues and or tire rubbing on the UCA. Any idea how i could figure that out?