5th Gen Tire Fitment Guide (need comments!)

[1engineer]

Alright. [MENTION=68981]jam23r1[/MENTION] had a great idea in the fact we needed a simple guide to help new members determine if they want to change tire size. As there are countless combinations of tire/wheel combinations it is impossible to build something simple that will help. With that in mind I put together a simple chart that shows what tire, with stock offset and backspace, will fit and what type of generic mods will be necessary if they choose that tire size. I need some of you to check this and critique it please. We can then refer tire questions to this chart. I know [MENTION=48772]Jesse1983[/MENTION] will take care of it once it is complete. It took quite a bit of time so take a look and see what you think!

 

[phillyd2]

With the Wheel Width Req'd numbers Centered while the other numbers appear to be Right justified the chart is unreadable and therefore useless. But nice try :drum:

 

[kenski]

With the Wheel Width Req'd numbers Centered while the other numbers appear to be Right justified the chart is unreadable and therefore useless. But nice try :drum:

Can you also include a column for the tire size?

Oh wait, there they are. I didn't see them since they were left justified.

 

[skimr]

greg,

In addition to your good friend's backhanded compliments, this is very nice. One observation based on the level of questions that folks seem to ask. You might consider adding a comment for what the +/- speedo diff means. Lots of folks with no real mechanical experience who will ask.

 

[philsey]

/Dr Bones McKoy voice/

Dammit [MENTION=6163]phillyd2[/MENTION] and [MENTION=88447]kenski[/MENTION], I'm an engineer, not a graphic artist.

Greg

 

[philsey]

I'm here for ya, pal.



Nice job, btw.

 

[chmura]

Think you should include 2 more sizes in there.

255 80 17 - 33.06" in diameter. Few people are running this size and it's a great size for the 5th gen. Very good off road and retains good mpg. Plus it fits in the spare wheel location. I believe this would be in the green/yellow zone.

285 75 17 - 33.83" in diameter. This would be in the red zone with required body mount chop, rear bump stop extender.

 

[jrandom]

Great! Thanks, very useful. I know in bigger charts having a single hue darker background for every other line item helps with visual separation, it may or may not help here.

 

[1engineer]

Revision C:
Thanks for the comments!

 

[phillyd2]

Never mind, it looked much better centered. :humble:

 

[jrandom]

Cool Did anyone ever figure out the offset and backspace on the TE rims by any chance?

 

[chmura]

Can you change 255 80 17 to yellow? You hardly get any rubbing with these. Worse case pushing the fender liner forward. They are definitely not red for sure in the category listing.

 

[Ducmonsta]

I've read the chart over and over and I can't seem to find what the factory backspacing and offset are for the factory wheels.

I know there's a "note" at the bottom about stock wheel configurations but showing an 18" wheel may lead someone to believe that this can work with aftermarket wheels.

One major fact that needs to be addressed is backspacing and offset. If the end user does not understand what those terms mean, he/she could have some serious fender damage or get stuck with some wheels and tires they ordered online that doesn't fit.

Let me see if I can explain this. If we take 2 18" wheels. One of them is 8" wide and the other is 10". Let's say both have the same backspacing, we'll call it 4.5". The offset of these wheels will be drastically different. The 8" wheel will have 0 offset while the 10" wheel will be something like -18.

So using the chart for a 285/65/18, there will be very little modifications required (yellow) for a 8" wide wheel. But use a 10" wide wheel and you're ripping fenders off.

I would also recommend leaving the wheel width req'd off. Or only use tires that will work with the factory wheel. People should be able to go to the tire manufactures website to determine what wheel width is required.

 

[1engineer]

I've read the chart over and over and I can't seem to find what the factory backspacing and offset are for the factory wheels.

I know there's a "note" at the bottom about stock wheel configurations but showing an 18" wheel may lead someone to believe that this can work with aftermarket wheels.

One major fact that needs to be addressed is backspacing and offset. If the end user does not understand what those terms mean, he/she could have some serious fender damage or get stuck with some wheels and tires they ordered online that doesn't fit.

Let me see if I can explain this. If we take 2 18" wheels. One of them is 8" wide and the other is 10". Let's say both have the same backspacing, we'll call it 4.5". The offset of these wheels will be drastically different. The 8" wheel will have 0 offset while the 10" wheel will be something like -18.

So using the chart for a 285/65/18, there will be very little modifications required (yellow) for a 8" wide wheel. But use a 10" wide wheel and you're ripping fenders off.

I would also recommend leaving the wheel width req'd off. Or only use tires that will work with the factory wheel. People should be able to go to the tire manufactures website to determine what wheel width is required.

I have asked for stock numbers and if I had them I would publish them. Wheel widths were added just as a fyi especially for the le crowd.

 

[harper7]

I've read the chart over and over and I can't seem to find what the factory backspacing and offset are for the factory wheels.

I know there's a "note" at the bottom about stock wheel configurations but showing an 18" wheel may lead someone to believe that this can work with aftermarket wheels.

One major fact that needs to be addressed is backspacing and offset. If the end user does not understand what those terms mean, he/she could have some serious fender damage or get stuck with some wheels and tires they ordered online that doesn't fit.

Let me see if I can explain this. If we take 2 18" wheels. One of them is 8" wide and the other is 10". Let's say both have the same backspacing, we'll call it 4.5". The offset of these wheels will be drastically different. The 8" wheel will have 0 offset while the 10" wheel will be something like -18.

So using the chart for a 285/65/18, there will be very little modifications required (yellow) for a 8" wide wheel. But use a 10" wide wheel and you're ripping fenders off.

I would also recommend leaving the wheel width req'd off. Or only use tires that will work with the factory wheel. People should be able to go to the tire manufactures website to determine what wheel width is required.

:iagree:
Although it's a tire fitting thread ,the wheel that's used adds another important variable to the fit.The caster(forward or aft) alignment specs are also another important variable.
Here are the specs I know for fact.
2010 Limited wheel 4.5" bs with a 7" width
2010 SR5 wheel 4.5" bs with a 7" width

I personally owned and measured the backspace of a stock LE and SR5 wheel and the factory back space was 4.5" and they were 7 inches wide. I also owned 4th Gen 07 Sport wheels and I measured the backspace to be 5.25" and with the 285/70/17 tire on it was within 1/16" of an inch from rubbing the UCA when the wheel was flexed down the whole way. Too close from comfort IMO and why I recommend less then 5.25" bs. Albeit I do have aftermarket UCA's and long travel shocks which brought them closer when fully extended(about 1 inch more extension) then if you have stock components.

I never owned a TE wheel so never measured the backspace on one of them. As I mentioned several times before.....nobody has ever measured and then reported the backspace of a stock TE wheel in the last 4 years they have been out. Nobody!Come on people......it's not that hard, however it is a little more challenging with the tire on because you need a straight edge of 16"-17" because it has to be flat on the backside of the wheel and not include the tire bulge.I'm betting that it's 4.5" or maybe 4.75" since it's a 7.5 width.

Here's where to measure and for even more info just look on youtube "how to measure wheel backspace"
Measure Wheel Backspacing - YouTube

Forgeline's Dave Schardt Explains How to Measure Backspace and Offset - YouTube



Like Bobby said,when it comes to realtionships with offsets and wheel widths ,that's the things alot of people just can't seem to grasp. The ONLY time comparing wheel offsets makes any sense is when comparing them of the EXACT same width wheel(rim).

That is why comparing back space with a wheel is much better way to compare because if you match the factory backspace by plus or minus 1/2" it will work no matter the width of the wheel. If you just have the offset from the manufacturer ,then the backspace can be found by using a offset chart......found by googling "offset chart" to check the chart to convert it to get the back space.

 

[limamike]

Greg - You're using RPM difference / original RPM to calculate speedometer difference, right? All of that looks good, but the only thing I'll caution for some people that might be a bit overly concerned about the speedometer reading is that 285/70/17 is spot-on for me, whereas 265s were reading low on my speedometer from the factory. I believe [MENTION=68685]Ducmonsta[/MENTION] has noticed the same thing, IIRC.

 

[1engineer]

:iagree:
Although it's a tire fitting thread ,the wheel that's used adds another important variable to the fit.The caster(forward or aft) alignment specs are also another important variable.
Here are the specs I know for fact.
2010 Limited wheel 4.5" bs with a 7" width
2010 SR5 wheel 4.5" bs with a 7" width

I personally owned and measured the backspace of a stock LE and SR5 wheel and the factory back space was 4.5" and they were 7 inches wide. I also owned 4th Gen 07 Sport wheels and I measured the backspace to be 5.25" and with the 285/70/17 tire on it was within 1/16" of an inch from rubbing the UCA when the wheel was flexed down the whole way. Too close from comfort IMO and why I recommend less then 5.25" bs. Albeit I do have aftermarket UCA's and long travel shocks which brought them closer when fully extended(about 1 inch more extension) then if you have stock components.

I never owned a TE wheel so never measured the backspace on one of them. As I mentioned several times before.....nobody has ever measured and then reported the backspace of a stock TE wheel in the last 4 years they have been out. Nobody!Come on people......it's not that hard, however it is a little more challenging with the tire on because you need a straight edge of 16"-17" because it has to be flat on the backside of the wheel and not include the tire bulge.I'm betting that it's 4.5" or maybe 4.75" since it's a 7.5 width.

Here's where to measure and for even more info just look on youtube "how to measure wheel backspace"
Measure Wheel Backspacing -

Like Bobby said,when it comes to realtionships with offsets and wheel widths ,that's the things alot of people just can't seem to grasp. The ONLY time comparing wheel offsets makes any sense is when comparing them of the EXACT same width wheel(rim).

That is why comparing back space with a wheel is much better way to compare because if you match the factory backspace by plus or minus 1/2" it will work no matter the width of the wheel. If you just have the offset from the manufacturer ,then the backspace can be found by using a offset chart......found by googling "offset chart" to check the chart to convert it to get the back space.

Absolutely [MENTION=8206]harper7[/MENTION]. My dilemma with this project is where do I stop?
I will put the BS and offset info in the chart. Will they understand it? I don't know. Probably not.

I've read the chart over and over and I can't seem to find what the factory backspacing and offset are for the factory wheels.

I know there's a "note" at the bottom about stock wheel configurations but showing an 18" wheel may lead someone to believe that this can work with aftermarket wheels.

One major fact that needs to be addressed is backspacing and offset. If the end user does not understand what those terms mean, he/she could have some serious fender damage or get stuck with some wheels and tires they ordered online that doesn't fit.

Let me see if I can explain this. If we take 2 18" wheels. One of them is 8" wide and the other is 10". Let's say both have the same backspacing, we'll call it 4.5". The offset of these wheels will be drastically different. The 8" wheel will have 0 offset while the 10" wheel will be something like -18.

So using the chart for a 285/65/18, there will be very little modifications required (yellow) for a 8" wide wheel. But use a 10" wide wheel and you're ripping fenders off.

I would also recommend leaving the wheel width req'd off. Or only use tires that will work with the factory wheel. People should be able to go to the tire manufactures website to determine what wheel width is required.

[MENTION=68685]Ducmonsta[/MENTION] Again I put that info specifically in there for the LE crowd as we both know what can happen with mismatched wheels and tires. As far as putting the 18" info there I will put a note for that too.

Greg - You're using RPM difference / original RPM to calculate speedometer difference, right? All of that looks good, but the only thing I'll caution for some people that might be a bit overly concerned about the speedometer reading is that 285/70/17 is spot-on for me, whereas 265s were reading low on my speedometer from the factory. I believe [MENTION=68685]Ducmonsta[/MENTION] has noticed the same thing, IIRC.

[MENTION=62008]limamike[/MENTION] You are right of course. The SAE J specs state a "range" on speedometer accuracy. The difference in the chart is a pure calculation, nothing else. It should give a decent idea of speed difference within a few mph though.

 

[BltByKrmn]

Wish someone had done this for the FJ before I bought wide tires, spacers and low offset wheels requiring a lift, body mount chop and mud flap removal. :tape:

 

[duanalto]

Holy cow...this is great!!!! Thank you!

 

[jam23r1]

Ok now that we have all the info make this a sticky!!!