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Discussion Starter #1
First post, just got a 2007 FJ and have a lead on some 17x8 wheels +15 offset with 305/70/17s mounted. I have a ToyTec 3" inch lift on the way and I won't be shy with the BMC but what does concern me is the +15 offset. From the Wheel/Fitment thread, looks like the recommended backspacing is 4-4.5". If my crash course on fitment calculations is accurate, the +15 will result in a backspacing of 3.9 inches of backspacing. I do plan on getting SPC Upper arms as well, will I have issues with this setup or is it something a set of spacers could fix? Looking forward to this project.
 

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First post, just got a 2007 FJ and have a lead on some 17x8 wheels +15 offset with 305/70/17s mounted. I have a ToyTec 3" inch lift on the way and I won't be shy with the BMC but what does concern me is the +15 offset. From the Wheel/Fitment thread, looks like the recommended backspacing is 4-4.5". If my crash course on fitment calculations is accurate, the +15 will result in a backspacing of 3.9 inches of backspacing. I do plan on getting SPC Upper arms as well, will I have issues with this setup or is it something a set of spacers could fix? Looking forward to this project.
You're wheels won't rub so you won't need UCAs, as with 3.9 BS, they'll be further away from the UCA. With the weight of the 305s and potential weight of the new wheels is where the 3.9" may hurt. You'll be putting an excess load on the outside of the wheel bearings, potentially causing premature wear. Having said that, an 8" wheel compared to a 9" or 10" will help some. You may only be looking at 10-20k miles of premature wear which probably wouldn't scare me away from using the wheels though.
 

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I think you might have it wrong...positive offset increases your backspacing. Stock FJ backspacing is 4.84".


With a 17 x 8 wheel the centerline will be 4.5" (rim width + approx 1 inch and then divided by 2) and then you add the offset to this number... so in the case you described with 15 mm of POSITIVE offset your backspacing will be 8.0 + 1.0 = 9.0" divided by 2 = 4.50" + 0.59" = 5.09" backspacing. Pretty sure that 5.09" backspacing will cause the inside of the tires to rub on the upper control arms given the OEM backspacing is 4.84".

Maybe you have it wrong and it is 17 x 8 wheel with -15mm (NEGATIVE OFFSET).... in which case this would put you at 3.91" backspacing. With 3.9" backspacing this will move the street side of the rim further outward by 0.93" plus an additional 0.50" of rim width over stock 7.5" rim width. What this means is the street side of the tire/wheel combo will be ~1.4" further outward than OEM setup (without accounting for tire bulge which we be more pronounced with a 305 width tire on an 8" rim). Where this can cause issues is when you turn the wheels and tires that they can hit on the mud flap and the body mount behind the mud flap.

With 305/70/17s and 3.9" backspacing I would say you have a very high likelihood of needing a BMC. And you may hit in other places during flex if you don't have a 2.5-3.0 lift.
 

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Discussion Starter #4
Thank you all for the detailed responses and you are correct, I calculated incorrectly and using a calculator netted the 5.09" backspacing you referenced. They are definitely +15 offset, they are TRD replica wheels. Will a spacer + BMC take care of the contact issues? What size spacer would you recommend? The 3 inch ToyTech lift is on the way so hopefully that will alleviate flex contact.
 

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I think you might have it wrong...positive offset increases your backspacing. Stock FJ backspacing is 4.84".


With a 17 x 8 wheel the centerline will be 4.5" (rim width + approx 1 inch and then divided by 2) and then you add the offset to this number... so in the case you described with 15 mm of POSITIVE offset your backspacing will be 8.0 + 1.0 = 9.0" divided by 2 = 4.50" + 0.59" = 5.09" backspacing. Pretty sure that 5.09" backspacing will cause the inside of the tires to rub on the upper control arms given the OEM backspacing is 4.84".

Maybe you have it wrong and it is 17 x 8 wheel with -15mm (NEGATIVE OFFSET).... in which case this would put you at 3.91" backspacing. With 3.9" backspacing this will move the street side of the rim further outward by 0.93" plus an additional 0.50" of rim width over stock 7.5" rim width. What this means is the street side of the tire/wheel combo will be ~1.4" further outward than OEM setup (without accounting for tire bulge which we be more pronounced with a 305 width tire on an 8" rim). Where this can cause issues is when you turn the wheels and tires that they can hit on the mud flap and the body mount behind the mud flap.

With 305/70/17s and 3.9" backspacing I would say you have a very high likelihood of needing a BMC. And you may hit in other places during flex if you don't have a 2.5-3.0 lift.
+15 is the right offset, which is 5.125 back spacing, which is common for a 17X8, more common is the 17X8.5 with -6 or 0 offset. I read this earlier as -15 also. 5 1/8 BS will probably result in 305s hitting the UCA.

Here is an easy to follow chart.

OFFSET CONVERSION CHART
MM OFFSET TO BACKSPACE IN INCHES

BACKSPACE3.25"3.5"3.75"4"4.25"4.5"4.75"5"5.25"5.5"5.75"6"6.25"6.5"6.75"7"7.25"7.5"7.75"8"8.25"8.5"8.75"9"9.25"9.5"
Wheel Width
5"61219253238445157636976
5.5"061219253238445157636976
6"-6061219253238445157636976
6.5"-12-6061219253238445157636976
7"-19-12-6061219253238445157636976
7.5"-25-19-12-6061219253238445157636976
8"-32-25-19-12-6061219253238445157636976
8.5"-38-32-25-19-12-6061219253238445157636976
9"-44-38-32-25-19-12-6061219253238445157636976
9.5"-51-44-38-32-25-19-12-6061219253238445157636976
10"-57-51-44-38-32-25-19-12-6061219253238445157636976
10.5"-63-57-51-44-38-32-25-19-12-6061219253238445157636976
11"-69-63-57-51-44-38-32-25-19-12-6061219253238445157636976
11.5"-75-69-63-57-51-44-38-32-25-19-12-6061219253238445157636976
12"-81-75-69-63-57-51-44-38-32-25-19-12-6061219253238445157636976
 

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Discussion Starter #6
Thank you for the quick reference chart & corrections. So at this point, I already planned on doing the BMC and trim any plastics I need to in order to get these to fit with minimal rubbing. As for UCA contact, I'll buy aftermarket UCAs without hesitation just to get that covered. I was thinking of the SPC UCAs as I had decent luck with them on my lifted Xterra but will that be enough clearance? The one thing I was trying to avoid was spacers but I'll do it if I have to, with all the data so far on the setup, what size spacer would I need or would it be best to just mount them up and take some measurements? I'm really like the idea of 305s on this rig and would like to get them to fit.

As for the type of driving I'll be doing, it'll be 80% street but we do like to hit the 4WD beach often in the summer time and drive in the sandy trails in the back. Nothing extreme but I will admit I'll try to keep up with the rest of the guys when there hooning around in the ruts. I broke an SPC arm right off the ball on my Xterra last time out there
 

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Thank you for the quick reference chart & corrections. So at this point, I already planned on doing the BMC and trim any plastics I need to in order to get these to fit with minimal rubbing. As for UCA contact, I'll buy aftermarket UCAs without hesitation just to get that covered. I was thinking of the SPC UCAs as I had decent luck with them on my lifted Xterra but will that be enough clearance? The one thing I was trying to avoid was spacers but I'll do it if I have to, with all the data so far on the setup, what size spacer would I need or would it be best to just mount them up and take some measurements? I'm really like the idea of 305s on this rig and would like to get them to fit.

As for the type of driving I'll be doing, it'll be 80% street but we do like to hit the 4WD beach often in the summer time and drive in the sandy trails in the back. Nothing extreme but I will admit I'll try to keep up with the rest of the guys when there hooning around in the ruts. I broke an SPC arm right off the ball on my Xterra last time out there
I run the new and improved SPC UCAs with no problems. The 305s on narrow wheels shouldn't require a BMC, unless you do use a spacer, which will push the tire back upon steering. If it were me, I'd try the wheels on first, then get an idea about the tire width with the UCA and body mount and then modify accordingly. If you still have your existing wheels and tires, you can at least put them back on after cycling the suspension and steering with the new ones on the ground.

Also if you are driving mostly paved roads, I'm not sure you would benefit from the SPCs over factory UCAs as they don't off a ton of extra clearance. They really just allow you more caster adjustments which is good for as much lift as you have. Don't get me wrong, they are definitely more robust. Toytecs come preset at 2.5" and unless they were cranked up, it can be relatively alignable on some FJs.
 

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Discussion Starter #8
Thanks for all the insight in this! I'll do a mock fit and see how it goes and take a look at all of the clearances, the information you all gave won't have me going in 100% blind. As for the lift, this is the lift I was just about to order: https://www.toyteclifts.com/ttboss-fj3k-boss-suspension-system-for-03-09-4runner-07-09-fj-03-09-gx470.html I'm looking to get 3 inches of lift, other than possible ride quality changes - I should be good to go on adjusting these to 3 inches correct? Is there another kit I should be looking at instead?
 

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My only caution is there are a lot of people that wasted money by upgrading suspension twice and even three times because there needs/desires changed and/or their knowledge changed. I always recommend spending a couple months researching all the possibilities before someone pulls the trigger on lift kits and making the wheel/tire combo decision. These should not be done independently.

The Toytec Boss Lift kit is a good system, but is not top of the line (and certainly not cheap). FYI....I have the Toytec Ultimate Lift which works fine for my needs because I only offroad occasionally (more of a dirt biker), but for many here that do more wheeling they are looking for systems with more travel, rebuildability, remote reservoirs, etc.
 

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My only caution is there are a lot of people that wasted money by upgrading suspension twice and even three times because there needs/desires changed and/or their knowledge changed. I always recommend spending a couple months researching all the possibilities before someone pulls the trigger on lift kits and making the wheel/tire combo decision. These should not be done independently.

The Toytec Boss Lift kit is a good system, but is not top of the line (and certainly not cheap). FYI....I have the Toytec Ultimate Lift which works fine for my needs because I only offroad occasionally (more of a dirt biker), but for many here that do more wheeling they are looking for systems with more travel, rebuildability, remote reservoirs, etc.
This SilvFx post is something I have lived. I've been through the Bilsteins, OME, and ICON products. Now giving the KINGS a shot. It gets more expensive not to buy the best the first time.


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This is a good entry level kit. I sell and install these very lifts as we are a certified Toytec dealer and installer. The guys are right about there being better suspensions out there but the price point is hard to beat, especially for someone who spends 80% of the time on the road. Just like everything else in life, the more you spend, the more refined a products you will get.

Having said that, I wouldn't recommend cranking these to the 3" mark unless you plan to install a heavy winch and bumper. For the 33s you are wanting to run, 2-3" is enough unless you are just wanting added height. If you do, I'd recommend using the diff drop spacers to help the CV angles. With any of these suspensions cranked up, you also lose ride quality, as you in effect raising the spring rate. Staying close to design rate is ideal with most aftermarket suspensions. As Sparky and Silver Fox mentioned, it doesn't take but a few years to go down a suspension rabbit hole, but most of the time there is a newbie wanting to save cash and will pick up your old(new) suspension for a fraction of the cost.

Merry Christmas!
 

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This SilvFx post is something I have lived. I've been through the Bilsteins, OME, and ICON products. Now giving the KINGS a shot. It gets more expensive not to buy the best the first time.


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This only makes sense if your FJ is purely an off-road toy. You guys suggesting rebuildable suspension setups for anyone who puts 15k+ miles a yr on their truck makes no sense. You have to rebuild those units and unless you’re doing it yourself....$$$$

I’m going to buy a GT3 because someday I’ll get on the racetrack and the standard 911 just won’t cut it...I’d be shocked if 10% of this forum ever out drives their suspension setup


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After this thing got going it became very obvious the OP will easily find something within an entry level setup to meet his requirements.


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After this thing got going it became very obvious the OP will easily find something within an entry level setup to meet his requirements.


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I’m still in in for spring rate conversation on pre-load.



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This only makes sense if your FJ is purely an off-road toy. You guys suggesting rebuildable suspension setups for anyone who puts 15k+ miles a yr on their truck makes no sense. You have to rebuild those units and unless you’re doing it yourself....$$$$

I’m going to buy a GT3 because someday I’ll get on the racetrack and the standard 911 just won’t cut it...I’d be shocked if 10% of this forum ever out drives their suspension setup


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I think the only suggestion is to take your time and research before you pull the trigger on whatever suspension upgrades you decide you need (e.g. know the full market of options, prices, advantages, disadvantages, trade-offs and planned usage before jumping in and spending their money). It can take months/years for people to figure out what they really want out of their FJ.

I see the same thing on a dirt bike forum that I frequent. People don't know what type of riding they like or plan to do ... or their tastes/desires evolve over time and they inevitably jump in too quickly without adequate research and buy the wrong bike that is ill suited for the type of riding they plan to do.
 

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Discussion Starter #17
All of this is very insightful. I've had my Xterra for the past 5 years on 3 inch spacer lift and 3 inch body lift rolling on 33s but want to step up a bit moving on to the FJ platform. Being 15 minutes from the ocean means the only type of off-road terrain I typically encounter is beach driving, muddy fields, and once in blue snow. While I wish we had more rough terrain to wheel on, I know I wouldn't get the full benefit of long travel suspension. I picked up the wheels and tires yesterday and looking to get a lift soon. Ideally I'd love to get 3 inches of total lift, given this information, any thoughts on a full kit? I will most definitely continue plowing through previous threads to get gather info.

Thanks & Merry Christmas!
 

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I’m curious how you increase spring rate on a linear spring by preloading the coil.


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If you tighten a progressive rate coil spring, you are preloading it more, giving it more spring rate. Ever notice that when you squeeze a spring together with your fingers, the tighter it gets towards total compression? Spring rates are based on the distance between stops in which it is assembled. Close that gap and you have more tension.
 

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I think this is the thread I'm looking for. I too recently purchased an FJ and have started my plan of attack to get it on the trails. Here's part of my problem--I'm running stock height, but the previous owner put a set of aftermarket 18"JR motorsport rims on, which I don't know the exact specs on. I'm currently running a Yokohama snow tire 275/65/18 which I plan on upgrading to an all terrain tire in the Spring. I'd like to do rims/tires/lift all at the same time and kill two birds with one stone. Stock rims for my NSSE are 17x7.5 +15 offset with a 4.5 backspacing. Contemplating a 3" lift, cuz I too drive my truck 90% of the time on normal roads and will only be able to wheel a handful of times throughout the year (and eventually I would like to add a bumper and winch, but that's def after suspension work) So my question is: how close to stock rims should I be to prevent rubbing or body mods with the lift? I've found a lot of rims that are 17" but vary in width and offset. Do I NEED to go down to a stock 17" rim or should I keep the 18's and just switch to different tires? I think this would lead to rubbing issues at full turn especially if I go to a taller tire. One of the debates I've seen on here is 275 vs 285 vs 295 for different driving situations, and don't know what will be best for my use. Trying to get all this accomplished without having to re-gear. Sorry for the long winded ramble, but any guidance will be much appreciated.
 
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