One more tire fitment question, I promise

[dhatcher]

I know, these questions are getting old but, I want to make sure I do it right the first time (and hopefully last!).

I've read through the tire fitment guide several times and the supporting articles as well as googling some stuff for myself.

As I understand backspacing and offset, it would seem, if I want to run 285/70/17 likely, I will need at least a 7.5" to 9" wheel. The trail premium I own comes with 7.5" wide wheels stock but, that seems like it might be pushing the limit for a 285/70r17. So, with the goal of trying not to get rub, I've surmised that, I would want to run a wheel with backspacing as close to stock (which appears to be 4.875 on the trail premium wheels) without going over.

Backspacing greater than 4.875 (say 5 for example) would mean more wheel width towards the UCAs, thus, higher chance for rubbing?

Backspacing say 4.5 - 4.75 would mean less wheel towards the UCAs and more towards the outer facing portion of the wheel.

Question (kind of a two part) is: A) is my understanding of backspacing correct? and... B) is 4.5 - 4.75 inch of backspacing completely reasonably, as in, not going to tear my wheel bearings off by being too far off from factory?

Thank you all for the help!

 

[1engineer]

I know, these questions are getting old but, I want to make sure I do it right the first time (and hopefully last!).

I've read through the tire fitment guide several times and the supporting articles as well as googling some stuff for myself.

As I understand backspacing and offset, it would seem, if I want to run 285/70/17 likely, I will need at least a 7.5" to 9" wheel. The trail premium I own comes with 7.5" wide wheels stock but, that seems like it might be pushing the limit for a 285/70r17. So, with the goal of trying not to get rub, I've surmised that, I would want to run a wheel with backspacing as close to stock (which appears to be 4.875 on the trail premium wheels) without going over.

Backspacing greater than 4.875 (say 5 for example) would mean more wheel width towards the UCAs, thus, higher chance for rubbing?

Backspacing say 4.5 - 4.75 would mean less wheel towards the UCAs and more towards the outer facing portion of the wheel.

Question (kind of a two part) is: A) is my understanding of backspacing correct? and... B) is 4.5 - 4.75 inch of backspacing completely reasonably, as in, not going to tear my wheel bearings off by being too far off from factory?

Thank you all for the help!

Here's the deal:
First, every 4Runner is not the same. What might rub for me might not rub for you. Why? Differences in manufacturing tolerances, difference in alignment (that's why they have a range) etc. So for anyone to tell you definitively that you will or will not rub is nonsense. The best you will get truthfully is in the ballpark.

Pushing the centerline of the tire AWAY from the vehicle will increase your chances of rubbing. Wheel spacers, wider wheel, higher offset will all do that.

With that said a 7 1/2 rim is just fine for a 285. There is no performance or safety advantage to a wider rim. Really.

You are choosing to go away from stock and run a bigger heavier tire. If you stick with stock wheel dimensions you might rub. You might have to do the fender liner mod. You might have to cut or remove the mud flap. If you decide to run a 9" high offset wheel or a wheel spacer you might have to do all this and a BMC. There is no other way to put this. This is fact and no amount of testimonials from other members will change this. You will lose some efficiency in the mpg department. Your wheel bearings will be under a higher load and will not have the same service life as a stock size tire and wheel. These are all knowns. Good luck.

 

[jwkilgore]

"Pushing the limits" for a 285-70R-17 would be putting them on a 7" wide wheel (lots of people do this on SR5's and Limiteds with no problems). With 7.5" Trail wheels you'll be perfectly fine.

Unless you want aftermarket wheels and are trying to justify the cost to your significant other.... in that case ignore the first paragraph and completely ignore the response above mine. Tell your SO that anyone putting 285-70-17 tires on anything less than 8.5" has a death wish.

And yes, with 285's you might rub inner wheel well plastic no matter the wheel (depends on the tolerances of your specific vehicle along with the skill of your alignment tech), but that's an easy fix. A few minutes with a heat gun or a drill and screwdriver and you're done. You shouldn't have to worry about rubbing anything metal.

 

[HerT4R]

These are all knowns.

^^^what he said! there are calculators for ALL of the things you are asking about available on the interwebz. please use this fancy tool called "google". its magical and will take you many many places that you would never have gone if you stay on this forum. Backspacing isn't just for 4runners. its for just about every vehicle with TIRES to think about.

:fish:

 

[dhatcher]

Here's the deal:
First, every 4Runner is not the same. What might rub for me might not rub for you. Why? Differences in manufacturing tolerances, difference in alignment (that's why they have a range) etc. So for anyone to tell you definitively that you will or will not rub is nonsense. The best you will get truthfully is in the ballpark.

Pushing the centerline of the tire AWAY from the vehicle will increase your chances of rubbing. Wheel spacers, wider wheel, higher offset will all do that.

With that said a 7 1/2 rim is just fine for a 285. There is no performance or safety advantage to a wider rim. Really.

You are choosing to go away from stock and run a bigger heavier tire. If you stick with stock wheel dimensions you might rub. You might have to do the fender liner mod. You might have to cut or remove the mud flap. If you decide to run a 9" high offset wheel or a wheel spacer you might have to do all this and a BMC. There is no other way to put this. This is fact and no amount of testimonials from other members will change this. You will lose some efficiency in the mpg department. Your wheel bearings will be under a higher load and will not have the same service life as a stock size tire and wheel. These are all knowns. Good luck.

Right, I understand no one can give me a definitive yes/no this will/will not cause rubbing. What I'm trying to do is push the odds more in my favor of minimal to no rubbing by making wise fitment choices.

Basically, right now I am looking at a wheel that is 17x8.5 with an offset of 0 and backspace of 4.75. This seems pretty much as close to stock as I can get with the exception of being an inch wider and being .125 inch shallower in backspace. By shallower, I mean that the inside of the wheel should be .125 of an inch less close to the uca than the stock wheel, that is what I am wondering if I am correct on. I realize the entire combination is likely to be heavier and reduce the service life of the wheel bearing but, not significantly so (hopefully). Like maybe the wheel bearing is reduced to 100K mile service life from 125K or would you think it would reduce the service like to say... 30K, 40k? Again, I realize no certainty can be said here due to manufacturing processes, I'm mostly looking for ... "from my experience" comments.

I intend to take off the mud flaps anyways, as generally mother nature will do that for you if you don't and you go off road anyways, so the rub I'm most concerned with is the UCAs. However, at this point, I'm planning to get the total chaos uca's with my lift kit and hopefully that would help as well (again, nothing certain, I realize).

 

[dhatcher]

^^^what he said! there are calculators for ALL of the things you are asking about available on the interwebz. please use this fancy tool called "google". its magical and will take you many many places that you would never have gone if you stay on this forum. Backspacing isn't just for 4runners. its for just about every vehicle with TIRES to think about.

:fish:

Right, as I mentioned in the original post, I used the magical int@rwebz and the resources located here in these forums. I'm trying to make sure I have a grasp on what it all means before I pull the trigger on spending any kind of money. Measure twice, cut once philosophy at work. Except I like to measure about 7-8 times before I cut, especially when it's cutting cash from my wallet.

 

[HerT4R]

Right, as I mentioned in the original post, I used the magical int@rwebz and the resources located here in these forums. I'm trying to make sure I have a grasp on what it all means before I pull the trigger on spending any kind of money. Measure twice, cut once philosophy at work. Except I like to measure about 7-8 times before I cut, especially when it's cutting cash from my wallet.

then start a spreadsheet, but please try NOT to clog up the forum with your repeated and similar threads that have been discussed ad nauseum :whipping2

 

[dhatcher]

then start a spreadsheet, but please try NOT to clog up the forum with your repeated and similar threads that have been discussed ad nauseum :whipping2

Look here Chief; you may want to go back and improve on your reading comprehension before you start trying to lay waste to "newbies." I understand how the forum and search functions work and how t3h googl3z work too.

I don't need to use the calculators, I've already used the calculators. I've used the calculators at:
https://www.tacomaworld.com/tirecalc and at Online Wheel and Tyre Fitment Calculator. Offset, Tyre Stretch and Speedo Error | Will They Fit

What I'm _trying_ to do now is understand the terminology better so that I completely understand what I'm buying and how it will fit, regardless if it rubs or not. My goal is to try to avoid the rubbing by understanding the terminology better, so that I know what numbers to look for when I'm using the calculators.

Now how about a little less :crybaby: from you and a little more quiet. If you don't like the thread, don't click it and don't read it. Especially if they are topics that, for you, have been discussed "ad nauseam."

 

[Brandonium]

If that is the case then you too should never post here as everything that can be discussed HAS been discussed as we are now entering the final year of Gen5..

I love how every one of these forums is the same. Search but do not ask but do not revive an old thread regarding a topic you might have a question about.

Thing is.. if you don't want to participate no one is forcing you to.

then start a spreadsheet, but please try NOT to clog up the forum with your repeated and similar threads that have been discussed ad nauseum :whipping2

 

[HerT4R]

If that is the case then you too should never post here as everything that can be discussed HAS been discussed as we are now entering the final year of Gen5..

I love how every one of these forums is the same. Search but do not ask but do not revive an old thread regarding a topic you might have a question about.

Thing is.. if you don't want to participate no one is forcing you to.

i have never said that, i actually love thread revivals as it keeps the info consolidated where it needs to be. And i dont START NEW THREADS for things that have been discussed, because theres already a thread for that. So i post there, even if the thread is a few years old.

youre standing up for a guy who has started at least 2 threads about very similar and already discussed items when he could have posted in the tire fitment or going bigger threads. theyre already out there and hes clogging up the main feed with his wasteful repetition.

 

[carlomagne]

285/70/17 M/T on an 8.5in wide tire -12mm offset with 1.25in spacers and no rubbing. No BMC, no cutting, and no fender mod needed. Doesn't even run while reversing and turning.




































/sarcasm

 

[HerT4R]

Look here Chief; you may want to go back and improve on your reading comprehension before you start trying to lay waste to "newbies." I understand how the forum and search functions work and how t3h googl3z work too.

oh man, i wasnt even trying to "lay waste" i dont think you want to see that side of me. then you will really need some ice for that burn.

I don't need to use the calculators, I've already used the calculators. I've used the calculators at:
https://www.tacomaworld.com/tirecalc and at Online Wheel and Tyre Fitment Calculator. Offset, Tyre Stretch and Speedo Error | Will They Fit

What I'm _trying_ to do now is understand the terminology better so that I completely understand what I'm buying and how it will fit, regardless if it rubs or not. My goal is to try to avoid the rubbing by understanding the terminology better, so that I know what numbers to look for when I'm using the calculators.

google has a dictionary feature and im sure typing in backspace, offset, width, and other wheel related terms will yield a plethora of search results. esp from these guys:

Now how about a little less :crybaby: from you and a little more quiet. If you don't like the thread, don't click it and don't read it. Especially if they are topics that, for you, have been discussed "ad nauseam."

not just ad nauseum for me, for other members, who have provided valuable input to this conversation on other threads that you are just way too different, or cool, or unique for. Did you even read the first two threads under "Modifications, Write-Ups, Quick Links, and FAQ's" --> "FAQ's", hint hint they are about tire fitment and going bigger.

 

[wfo9]

I did not read all the responses.. But I can tell you that your general understanding is correct. I appreciate when people try to educate themselves and don't just ask questions hoping others will do their thinking for them.

Here is what you need to know. Ideal backspacing with 285s on the 5th gen is ~4.5". The stock wheels 7.5" with 4.875" BS will work to an extent, but depending on the UCA (most people want aftermarket). You will get minor rub on the UCA (depends on tire and alignment).

Here is the deal with backspacing and track width. The less backspacing the greater the track width. But... (and this is huge), as you decrease backspacing you increase the scrub radius of your steering geometry. This puts more stress on everything and (the most important part) causes the wheels to move more fore and aft as you go lock to lock (causing more potential for rub).

Now, if you increase the track width with longer control arms (upper and lower.. think long or mid travel setups) The scrub radius and steering geometry can stay the same.

There are many benefits to increasing track width in terms of performance and handeling, but as usual. No free lunch. It's all compromises.


As far as the same questions over and over go.. I get it. It gets old, but honestly most people still don't understand this stuff in detail. So instead of explaining it and being done with it. They just get tired of hearing about it. When you have done something before.. you tend to have an appreciation for the learning curve and the nuance details that make it all finally click.