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Discussion Starter #1
I'm wondering what the maximum overall tire diameter is for a stock 2019 WRX, without rubbing.

My actual goal - which the above helps me get a better grasp on - is to discern the maximum diameter I can run using a 16x7 +20 wheel, but I doubt anyone can answer that because it's such an uncommon configuration. And to make things more confusing, offset may actually be larger; I'm speaking with someone who can confirm Sparco Terras in 16x7 +45 will clear the brakes on my WRX with the use of a 25mm spacer, and I've asked them to check if I can reduce the spacer size at all because I want to minimize spacer use.

The secondary question, also to assist in reaching my primary goal:
How much will decreasing offset affect whether a wheel/tire fits without rubbing? I ask because this guy below made 215/60 tires work, but he's actually running the +45 offset without a spacer effectively reducing it like I will have:
https://www.reddit.com/r/subaru/comments/95zuoq I should note that I don't know if this guy is experiencing rubbing...but I don't think so based on his comments, and I also doubt it because while the offset is lower than stock, the width is also lower, the end result being more fender room, and the overall diameter is only 11mm larger, according to this calculator:

Fingers crossed for the ability to run 215/65 tires - as that gives me more than 1 A/T option, and would be cheaper - but I expect that will be too large :(
The guy on Reddit even says "I’m thinking of getting BFG KO2’s in 215/65/16 down the road but I’m worried that the extra tire might cause some rubbing"
 

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Well to be fair any wheel will fit the brakes if you poke them out so far the brakes are not inside the wheel.

You can check the wheel fitment threads at nasioc, but I've not seen anything like this talked about here outside of a rally thread a while back.

Spacers are total crap. I don't care what kind avoid them and buy wheels that fit appropriately. If said wheels don't exist find someone that can make them for you.

Also, what purpose does this serve? Rally inspired look or something?
 

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Exactly what are you trying to do here?
 

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Discussion Starter #4
Well to be fair any wheel will fit the brakes if you poke them out so far the brakes are not inside the wheel.

You can check the wheel fitment threads at nasioc, but I've not seen anything like this talked about here outside of a rally thread a while back.

Spacers are total crap. I don't care what kind avoid them and buy wheels that fit appropriately. If said wheels don't exist find someone that can make them for you.

Also, what purpose does this serve? Rally inspired look or something?
True, I suppose I could run no wheels, just rubber cylinders with ~200mm "spacers" in the form of poles attaching my "tires" 😁
Yeah I've done a lot of searching, seen plenty of working fitments, but no mention on limits- what doesn't work.
I've done plenty of research on spacers, which is why I want to minimize them.
Basically: It's my daily, but it's far too much of a street car for my liking in stock form; I want to maximize tire wall to soften the ride, make it better for pot-hole ridden gravel/dirt/off-road purposes, the occasional rallycross- all without changing suspension/brakes, for now. The end goal is some suspension changes (height, travel, oversteer) for the reasons listed - to make the car more rally-inclined than rigid/low - but that's an investment, and I'm just preparing for winter currently. Essentially, I'm buying wheels/tires for the upcoming winter, and am trying to future-proof for a rally-esque use-case.

Exactly what are you trying to do here?
Not sure I understand the question since I defined my precise goal- maybe that last statement in my response to XJman answers your question?
 

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All of this depends on your definition of "works" what you described won't work at all per my opinion, scrub radius is out of spec and at tires add substantial weight and heft to a suspension not designed for it, the diameter is off causing the mph and mileage on the vehicle to be wrong, and technically would require you to fill out a false odometer reading box for the title.

Will what your asking for bolt on? Probably. Will it fit right? No. Will the overall performance and driving feel tank? Yes.

You are asking a car to do the work of an SUV and I think you may have purchased the wrong platform for those tasks. A wrx and a rally car have nothing in common besides the name really. Suspensions are designed entirely around that use. The wrx is designed as a street car entirely. It can deal with some roughish roads and some dirt paths, but even with at tires you are pissing away effort. Without substantial modification it won't be any better off road than any other vehicle really.

For winter a set of nokian tires will do more than whatever it is you are attempting to accomplish will do for handling and safety.
 

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Discussion Starter #6 (Edited)
I mean, I'll be buying a random beater for rally, which is what most people use- so no I definitely didn't buy the wrong platform considering most people are out there tearing it up in stock atrocities not remotely designed for that purpose, lol. And again, it's a daily driver, so no need to overthink performance.
Honestly every day that goes by I love my decision to buy the WRX more (even instead of the STI). Ugh. I love this car so much.

I defined what "doesn't work" as 'rubbing'. Like I said, the only question I'm really asking here is what diameter the stock car can handle. That said, I am curious, what experience do you have to back your concerns? I don't mean to be rude - normally I'd just ask for input everywhere and let it add up to a decision in my mind - but things get complicated when I'm putting trust in a racing company founded by a professional rally driver for input on a configuration which I'm readily aware goes against established rules of thumb (meaning, to some degree, I do need to ignore concerns raised by people who might just be parroting what someone else on the internet was parroting from someone else on the internet parroting-...).
I will say the person I'm in contact with hasn't addressed tires much, simply recommending Geolandar A/T G015s in 215/60- let's say I go with those (I could also do 205/60 which makes overall diameter almost identical to stock). Can you elaborate on the following?
  • How increasing scrub radius by 33mm (from an assumed 0mm) will negatively affect me (compared to +45 offset increasing scrub radius by 8mm- as done by the person on Reddit)- is this your only real concern if I'm keeping diameter close to stock?
  • How increasing overall diameter by 11mm (1.7%) will negatively affect me
  • How altering radial density of the overall wheel/tire mass will negatively affect me [sure the tire is heavier, but the wheel should be lighter]
I should say I already know the answers to these questions in a general sense, the only reason I ask is under the assumption you might have more direct experience with these changes to this degree, and specifically on this car.

Thanks for the responses!

Will what your asking for bolt on? Probably.
Assuming I might not buy the correct bolt pattern? Now that's just silly 😛
 

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Not sure I understand the question since I defined my precise goal- maybe that last statement in my response to XJman answers your question?
No, you said what you wanted to do, not WHY you were attempting to do those things.
 

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Discussion Starter #8
And you asked me what I was trying to do, not why I was doing it...
But indeed, this is why:
It's my daily, but it's far too much of a street car for my liking in stock form; I want to maximize tire wall to soften the ride, make it better for pot-hole ridden gravel/dirt/off-road purposes, the occasional rallycross- all without changing suspension/brakes, for now. The end goal is some suspension changes (height, travel, oversteer) for the reasons listed - to make the car more rally-inclined than rigid/low - but that's an investment, and I'm just preparing for winter currently. Essentially, I'm buying wheels/tires for the upcoming winter, and am trying to future-proof for a rally-esque use-case.
 

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Wheel diameter and weight are related, but a smaller wheel does not always weigh less than larger wheel. The sparcos are likely to be hefty as hell as they are geared toward heavier use and possibly entry rally classifications.

Then add an AT tire that's way beefier than any all season or summer tire and the weight grows. You'll be heavier.

So you'll have heavy tires, heavy wheels, poked way out. Your steering and braking will suffer, the leverage on the steering and suspension will be increased and it will feel like you are driving a 90s chrysler.

You do you, but there is no positive outcome of this unless some rally look is your goal.
 

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Discussion Starter #10
I understand size isn't the only factor- just checked though, and they're 3 pounds lighter than my stock wheels.
What's really surprising to me though is that my stock (performance package) tires are actually the same weight (25lb) as the Geolandars in 215/60/16...though I suppose that's not so odd considering while the A/Ts have more wall, they're thinner (most 245/40/18s actually seem to be heavier- the 5 cheapest and 5 most expensive performance/touring/summer tires I checked out averaged to 26lbs).

So anyway, I'll actually be reducing unsprung mass, which is neat.

Now I just have to discern if the increased scrub radius is actually going to feel significantly worse...wish I could just test drive the setup :/

Anyone able to talk on the feel of going from 0 to 31mm scrub radius, or 18% of [the 170mm] tread width?
 

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Discussion Starter #12
Oh weird, yeah the Yokohama site puts them at 27.3. I was looking at tirerack; Goodyear/Dunlap doesn't list the weight of my Sport Maxx RTs, but discounttire actually puts mine 1lb heavier too.
 

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Those rotas and geolanders were stupid heavy. It's also why i know precisely why the path you are walking is a sad miserable one.

There is more to all this. AT tires are huge thick skinned concrete blocks compared to your traditional passenger car tire. They, surprisingly, are still designed to survive sidewall and tread abuse that a street tire would not survive. It's not the 3/4 inch thick sidewalls on the tires on my jeep, but it's a notable difference. This means that even with the taller sidewall it's going to beat the brakes off of you. And handling will be floaty and very poor feeling.

I won't stop you from your endeavors, but it's a path I've dealt with and it sucked.
 

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Discussion Starter #14
Those rotas and geolanders were stupid heavy. It's also why i know precisely why the path you are walking is a sad miserable one.

There is more to all this. AT tires are huge thick skinned concrete blocks compared to your traditional passenger car tire. They, surprisingly, are still designed to survive sidewall and tread abuse that a street tire would not survive. It's not the 3/4 inch thick sidewalls on the tires on my jeep, but it's a notable difference. This means that even with the taller sidewall it's going to beat the brakes off of you. And handling will be floaty and very poor feeling.

I won't stop you from your endeavors, but it's a path I've dealt with and it sucked.
Well I appreciate the input! Even if I do send it, at least I won't be blind-sided if it does turn out miserable- I'll be able to atone with the fact that I did it to myself with fair warning, lol.

So what was the exact before/after setup that you hated?
Were you on 235/45-17x8ET53 before moving to 215/60? And what are the wheel specs?
 

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Discussion Starter #15 (Edited)
Just gonna vomit some notes here in case someone finds them useful...

Focusing on understanding what I can expect from increasing scrub radius by x, I found the following, which is the most confident statement on scrub radius increase as a concept that I've found, made by Andrew of Racecomp Engineering- who appears to be, at the very least, involved in BRZ rallycross.
The key statement for me is:
"
a very large [scrub radius] value can feel pretty awful in terms of steering kickback, effort, and also do some funky things with toe change.
I don't have any set numbers for you guys, but -10mm in offset from stock is certainly fine IMO.
"
(statement made in a BRZ forum, where it appears -10mm offset translates to +10mm scrub radius via 215/45-17x7ET48- same increase for a VA WRX)

As an aside on spacers, I also stumbled upon this statement which surprised me a bit:
"The TMG CS-V3 cup cars have optional 10mm spacers front and back to increase track width with et48 ultraleggeras. In case you didn't know, TMG are Toyota's offical motorsport team in Europe that build the le mans cars and won all those rally championships in the Celicas.... if they say its okay to run those spacers. ... "

Here is some subjective input from random people on the internet...
[scrub radius increase (mm) where OE scrub radius is assumed to be 0; is calculated based on VA WRX specs unless specified] :: [statement context] :: [provided feedback on steering feel change]
  • 54 (from 235/45-17x8ET53 to 285/35-18x10.5ET22 with additional 25mm spacer) :: WRX/STI forum ::
    I can’t really relate it to stock because I’ve done a lot of suspension mods too. It’s not too bad, I went with a lighter wheel setup so it’s good.
  • 11 (from 245/35-19x8.5ET55 to 215/60-17x8ET38) :: WRX/STI forum ::
    As far as this specific setup, so far my review is overall positive. The tires obviously have less grip than my summer wheels (duh), so my car tends to understeer more than I'm used to. I don't know if it's imagined or not, but I think I can feel the larger radius tires - my car feels slightly less powerful and I feel like I need to hit the brake 5% harder than I'm used to.
    I had no idea scrub radius was a thing, but totally makes sense. I'm a little more squeaky doing tight turns in parking garages, and the steering feels a little heavier, so if I had to guess I increased my scrub radius a tiny bit. It feels safe and stable enough on the road at both high and low speed, though I'm curious to test out what they talk about where driving through water will yank your steering one way or the other. I did have it out in the desert messing around in all sorts of terrain (sand, dirt, rocks), and didn't notice anything funky. And of course the fact I was able to easily play around on that stuff is a huge plus to this!
    You hear about people doing lifts/wheels on their car and taking it out for the first drive and being like "Oh my god I turned it into a death trap". I had the opposite reaction, I was like "omg I hope I didn't break it", then took it out for the first drive and my reaction was "Oh, this is fine." Any feelings I talk about above are at max, like a 5% difference from stock.
  • 36 front, 74 rear (38mm spacer front, 76mm spacer rear) :: rallycross group ::
    Less body roll around corners. Steering response nearly the same though the back seems to want to let go more easily now. Overall worth the time and money.
  • 38 (OE scrub radius of -19, from +53 to +15) :: rallycross group ::
    That changed my scrub radius from negative to positive by about the same amount. [....] Positive SR causes the wheels to want to toe in under acceleration and toe out under braking. I have not really noticed this, but I don't drive hard on tarmac and on loose surfaces, the grip in low enough that I think the tires break loose before there is significant toe change. Also, usually if I am braking at the limit it is in preparation for a corner and my steering inputs overpower any effect I would feel from the toe out.
  • 23 (from 245/35-19x8.5ET55 to 255/35-18x9.5ET35) ::
    Not much difference in steering feel. Traction definitely increased, corners well at high speed, and seems to brake more quickly.
  • 20 (from 245/40-18x8.5ET55 to 255/35-18x9.5ET38) :: WRX/STI group ::
    I've had a whiteline track suspension set up for a while and while the car already drives good, made a world of difference. Drives better but hair more noise.
  • 20 (from 245/40-18x8.5ET55 or 235/40-17x8ET55 to same minus 20 offset) :: WRX/STI group ::
    It made a huge difference in cornering stability feel. My new rims are much lighter also, that would contribute
  • 19 (from 245/40-18x8.5ET55 to 265/35(?)-18x9.5ET38) :: WRX/STI group ::
    The car itself, not the steering wheel, feels a lot more planted. 245 stock to 265 on each tire is a huge improvement for grip. I miss is. I am on 245 now and the car feels floaty at times. This could be due to my driving as well, as I do spirit drive a lot. The 2015 felt planted majority of the time.
  • -24 (from 185/65-15x6ET25 to 215/45-17x7ET48) :: rallycross group ::
    Not much change noticed from the wheels and tires from a feel perspective. The alignment does make a difference in feel.
    Intent was a slightly track width, but narrower footprint so the tires would dig into loose surfaces better.
  • <~22-29 (from 245/45-18x8.5ET55? to 215(?)/60(?)-16x7ET45 or from 225(?)/65(?)-17x7ET55 to 215(?)/75(?)-16x7ET45 with additional 25mm spacer) :: rally racing company employee ::
    The driver of the Outback loves the car, I would have to explain to him why it might be an issue for him to even realise what I was referring to because it really isn't noticeable at all.
  • ~22-29 (from ? to 255/70-16x8+20) :: rally racing company employee ::
    We also have a 2017 Outback (shop car, same brake setup) with 16x8 +20 fuel vector wheels they are very heavy, almost 30 lbs with 255-70-16 BFG K02 each tire/wheel is almost 70lbs and the scrub radius is worse but is still barely noticeable when you drive it. We've used it for Road Rallies, pre-running the course for stage rallies, we've loaned it to organizers for the course opening and everybody absolutely loves driving it and these extremely experienced people.
  • 12 (from 245/40-18x8.5ET55 to 265/35-18x9.5ET45) :: WRX/STI group ::
    hard for me to isolate the changes (wider tyres/rims, slight offset change, grippier compound) but steering feel is slightly heavier and it just grips like shit on a rag
    I will call out that this wheel/tyre size is absolutely ideal for the VA platform - at least according to the japs. If you look through any JDM hyper rev magazine focused on the VA chassis, every feature car runs the exact same 18x9.5 +45 265/35R18 setup.
Gotta love that mad lad with SEVENTY SIX MILLIMETRE spacers- I even clarified to make sure we were talking about the same "offset". The man bolted a 1.5in spacer to his hub...and then bolted another 1.5in spacer on top of it. The man doesn't play by the rules!
 

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Lots of information and a very useful post, thanks! It's going to help people in the future.
 

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Well I appreciate the input! Even if I do send it, at least I won't be blind-sided if it does turn out miserable- I'll be able to atone with the fact that I did it to myself with fair warning, lol.

So what was the exact before/after setup that you hated?
Were you on 235/45-17x8ET53 before moving to 215/60? And what are the wheel specs?
With the ats the ride was hard, steering imprecise, and braking was dodgy. It genuinely felt like driving a neon or something. That was including a lift. Just swapping to factory sized snow tires on factory wheels with the lift tightened it up a lot. It wasn't summer tire and performance brake kit tight but it felt modern.

After spending a lot of money redoing the suspension and some other things that i don't remember all of at this moment all related to the lift it actually drove and was exciting. Besides my 2000 XJ Cherokee it's the only vehicle i regret selling
 

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Discussion Starter #18 (Edited)
Lots of information and a very useful post, thanks! It's going to help people in the future.
Hope so! Honestly wish I could change the title now since the discussion veered pretty quick, haha, but shouldn't matter too much.

With the ats the ride was hard, steering imprecise, and braking was dodgy. It genuinely felt like driving a neon or something. That was including a lift. Just swapping to factory sized snow tires on factory wheels with the lift tightened it up a lot. It wasn't summer tire and performance brake kit tight but it felt modern.

After spending a lot of money redoing the suspension and some other things that i don't remember all of at this moment all related to the lift it actually drove and was exciting. Besides my 2000 XJ Cherokee it's the only vehicle i regret selling
Damn. Yeah I'm hoping to keep this car basically forever, and judging by my love for it increasing every day, I think my odds are pretty good!

And on that note...let's hope I'm not wasting money on a mistake, because I went ahead and pulled the trigger on the wheels (with plans for the 215/60 Geolandars).

I did so for two reasons:
  1. Minimal risk: If I really hate the results, I can size down my brakes and remove the spacers- expensive and annoying, but not the end of the world. I expect the spacing to be the most significant factor, but if I also really think 215/60 is too big, I can eventually go down a bit to almost perfectly match the stock diameter.
  2. Plausible reward: The guy helping me at Primitive Racing actually had a lot of positivity to provide in the form of anecdote, at least for rally usage (I edited my compilation of subjective data above to include it); with that and not many other people vocalizing displeasure with similar or more drastic changes, I think I'll be fine- especially because performance on pavement isn't something I really car about. This is also all under the assumption I'll actually be using 25mm spacers- I'm still hoping I can reduce that (Primitive Racing just doesn't use shorter spacers because doing so requires replacing studs- they don't actually know the minimum spacing necessary for this setup).
For anyone curious how it goes, I'll try to remember to come back here and post the results.
 
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