Wheel Fitment Help

[briang0901]

Before I begin, know that I scoured every source I could find for this question and everything I read was literally, yes it works or no it doesn't. Couldn't find a single definitive answer.

I have a set of 17x9 +45 RPF1s w/ 245/40/17 R-S4s that I want to install on my stock GR86. I had thought they would fit based on previous research before I bought them, but apparently I didn't look hard enough.

Can the last vestiges of this community tell me what I need to do to make these work without going down the coilover route?

I really dont want to use spacers since I intend to track/autox the car. My plan was to use lowering springers, pedders top hats, and camber bolts to solve the fitment issue but I am not sure on its thats even an option.

Thanks in advance y'all.

[RT-BRZ]

Originally Posted by briang0901

Before I begin, know that I scoured every source I could find for this question and everything I read was literally, yes it works or no it doesn't. Couldn't find a single definitive answer.

I have a set of 17x9 +45 RPF1s w/ 245/40/17 R-S4s that I want to install on my stock GR86. I had thought they would fit based on previous research before I bought them, but apparently I didn't look hard enough.

Can the last vestiges of this community tell me what I need to do to make these work without going down the coilover route?

I really dont want to use spacers since I intend to track/autox the car. My plan was to use lowering springers, pedders top hats, and camber bolts to solve the fitment issue but I am not sure on its thats even an option.

Thanks in advance y'all.

Everything I can find says that the OEM wheel offset (regardless of OEM wheel style) is +48mm. You've added ~37mm of wheel/tire width over the widest OEM wheel and you've only changed your offset by -3mm with your wheels. It is likely you wouldn't have to account for all of the remaining 34mm of offset but probably at least half of it to get clearance. So, at a minimum, I would say 15mm of spacers are in order.

So, you don't want to use spacers and you don't want to install coilovers. I'm guessing you want to keep the same wheels. There is likely not a combination of adjustments that will get you there if those are your restrictions.

[briang0901]

Originally Posted by RT-BRZ

Everything I can find says that the OEM wheel offset (regardless of OEM wheel style) is +48mm. You've added ~37mm of wheel/tire width over the widest OEM wheel and you've only changed your offset by -3mm with your wheels. It is likely you wouldn't have to account for all of the remaining 34mm of offset but probably at least half of it to get clearance. So, at a minimum, I would say 15mm of spacers are in order.

So, you don't want to use spacers and you don't want to install coilovers. I'm guessing you want to keep the same wheels. There is likely not a combination of adjustments that will get you there if those are your restrictions.

Yea but what is the risk of running spacers until heavy driving?

[RT-BRZ]

Originally Posted by briang0901

Yea but what is the risk of running spacers until heavy driving?

Well, it's all about how you go about it. Personally, I don't like bolt on spacers for anything. That being said, I use spacers but I have long studs and pass through them. However, 3-1/4" studs are a pain. An alternative is the ARP 2-3/4" studs that should allow you to run a good set of hub centric spacers that are 15mm and I would trust that setup for racing.

2-3/4" ARP studs should be able to be installed without removing the hubs.

It's all about where you want to make your investments.

[cmiovino]

I went down this route when I was in street class (CS and then DS) with my first gen. There weren't a lot of good 5x100 wheels I liked that were 17x7.5. I know yours are 9", but I'll get to that in a second.

With the stock +48 and some STI +53 offset wheels, both with 3mm spacers, there was very little room between the strut and the top of the tire with only 1 degree of camber.... with a 225. The +50 effective offset combo cleared, but literally by a hair. The +45 combo fit with 2mm more space, which worked.

The other thing to think about is camber. The above was with the OEM crash bolts and not running true aftermarket camber bolts to get into the 2 degree area. That extra degree is a lot in terms of millimeters of wheel tilt. If you're going on a track and tossing in aftermarket camber bolts to get -2 with even a 225, it might clear with the +45 offset, but it would be damn close. The strut just don't work well with camber. Coilovers open up the front so much... literally by an inch or more.

So a 245 on a 9" with the same offset? Hell no. The 245, although being 20mm wider "section width", usually have an even wider "tread width" than a 225... aka, the tread section is just wider than you'd think. Even on paper just going off section width, you're adding 10mm to each side (disregarding wheel width to keep this simple). 245's in most 200TW tires start getting fat at the tread section, so factor in about 12-13mm there over 10mm.

I can confirm autocross guys are making 245's fit and have to stick to the +/-7mm rule in street class. So with a +48 wheel stock and that 7mm allowance, IIRC they're tossing on 7mm spacers on extended ARP lug nuts and running a +48 wheel (effectively a +41 offset). This is because +48 wheel offsets are relatively common. If it worked with a +45 wheel and 245's, they'd all run that and I would have tossed on my 3mm spacers and 245's, but it wouldn't.

TDLR: You'll need a 7mm spacer and extended studs in the front to make a +45 work. This is only in the front too - rears you'll clear fine.

[briang0901]

Thanks for the advice and recommendation, just out of curiosity, if I ran a 235 or 225, would that negate the need for spacers?

[briang0901]

Originally Posted by RT-BRZ

Well, it's all about how you go about it. Personally, I don't like bolt on spacers for anything. That being said, I use spacers but I have long studs and pass through them. However, 3-1/4" studs are a pain. An alternative is the ARP 2-3/4" studs that should allow you to run a good set of hub centric spacers that are 15mm and I would trust that setup for racing.

2-3/4" ARP studs should be able to be installed without removing the hubs.

It's all about where you want to make your investments.

Which spacers would you recommend?

[RT-BRZ]

Originally Posted by briang0901

Which spacers would you recommend?

Honestly, I just got some 25mm hub centric (56.1) spacers from ebay. Since I was passing through my bolts versus bolting on the spacer and then bolting the wheel to the spacer, I didn't feel like a special brand was necessary. I also bought a set of 5mm spacers to do the exact some thing for a different set of wheels.

However, I'm sure that there are others that have a preference for the right brand/quality of spacer to recommend.

[OkieSnuffBox]

https://www.systemmotorsports.blog/b...r86-subaru-brz

Although I believe this assumes coilovers because they give you more inboard room. Many of us on coilovers are running 18x9.5 ET45, 245/35.