Tire fitment issues in the rear

[OkieSnuffBox]

Originally Posted by jbug187

I've had this car for almost three months and have had a great time doing some small mods (PowerStop brake pads, Castrol SRF brake fluid, K&N Air Filter, TRD Duckbill Spoiler) and taking it to the track for a couple of HPDE1 events. I live in the Northeast and want to get a separate set of wheels / tires for non-Winter daily driver and track day duty and could really use some advice as I've read through this entire thread and am still not confident about fitment.

I'd like to get flush fitment and avoid replacing the stock suspension or rolling / pulling fenders if possible. I like the Aodhan AH09 (and its price) which comes in 18", 8.5", ET35, but I'm not sure if the offset is too aggressive on a 8.5" wide wheel (I know it would be on a 9.5" wheel). In this post from Panda Grahams it looks like he was able to achieve flush fitment with a 0.5" thinner wheel and I'd be using the same 225 tire size. With that being said I don't see any Gen2 BRZs or 86s with the AH09 wheels online, which doesn't make me hopeful.

To throw another variable into the mix I'll also be installing these fender flares which say they "add another 8mm" (inspiration here). The installation guide for the fender flares requires minimal drilling inside the wheel well so I think this is something I could do on my own without any invasive cutting / welding. I guess it's fairly obvious the tires will looks more 'tucked' with the additional 8mm added to fender? Ultimately, I'm looking for a flush fitment without any rubbing. If anyone sees any obvious mistakes with AH09 / 225 + 40R / fender flare setup, please let me know.

Just curious why you would bother with flares for such a mild fitment on stock suspension?

If you aren't cutting or at least flaring the stock fenders underneath, you're not really going to gain any extra clearance by adding flares. So you'll have sunken in wheels with flares on stock suspension?

I know looks are subjective, but that's going to look pretty bad IMHO.

[jbug187]

Originally Posted by OkieSnuffBox

Just curious why you would bother with flares for such a mild fitment on stock suspension?

If you aren't cutting or at least flaring the stock fenders underneath, you're not really going to gain any extra clearance by adding flares. So you'll have sunken in wheels with flares on stock suspension?

I know looks are subjective, but that's going to look pretty bad IMHO.

Agree that sunken wheels are going to make the flares look pretty bad. I don't have any experience with fitment, but here's my thought process on trying to get the wheels flush with the flares:

1. Panda Grahams was able to get get what looks like flush fitment running a 8.0" wheel with the same 35 offset here
2. With an 8.5" wheel there would be an additional 0.25" sticking out from the fender which translates to an additional 6.35mm
3. The fender flares say they add 8mm so would be 1.65mm 'less flush' (8mm - 6.35mm)
4. Maybe add a 3mm spacer to make slightly more aggressive?

Please let me know if these numbers check out or if I'm off base. Another thing I have no experience with (there's a trend here) is rolling fenders / pulling fenders / cutting. Is that needed because there would be rubbing on stock suspension, or only if the car is lowered? Thanks for the help.

[timurrrr]

Tried Falken RT660 245/40R17 on Enkei RPF1 17x9 +45.
I have Verus RLCA and temporarily have coilovers from a gen1 car.
~1" drop vs stock, and -2.5º camber at ride height (so ~0.5º additional camber compared to stock arms?).

To check for clearance issues, I put the car on a fork lift, disconnected the rear end links, and fully loosened the spring seats (ideally I should have removed the spring altogether, but I didn't have time to do that).
Then I used a hydraulic jack to raise one of the rear wheels at a time, until the rear jacking points started to rise off the hockey pucks on the arms of the lift.

Remember that this may or may not represent what happens to your suspension in the real world.
If you only ever drive on mostly flat surfaces, and your spring rates are super high (autox'ers?), then the wheel may never go that deep into the wheel well.

However, if you have softer spring rates and for example you go down The Corkscrew at Laguna Seca, chances are your wheel will go into the wheel well as deep as the suspension geometry allows.

The other factor that you may or may not want to consider is sidewall flex of the loaded outside tire. I don't have enough data to say how much the top of a laterally loaded rotating tire moves compared to only vertically loaded static tire, or even in which direction.

Anyhow, here are the photos. Use your own judgement to draw conclusions.

1) First test, no adjustments vs gen1 setup.
The rear coilovers were already set up to have ~7 mm less compression travel than recommended by the installation instructions that came with them. Notice that some of the rubber "antennas" turned into J's.
Honestly I don't even remember if I jacked the wheel all the way at that point or stopped early. It's THAT close.



2) Adjusted the coilover to have 18 mm (!!!) less compression travel than recommended.
Now I can squeeze a caliper in between the tire and the fender liner.
Not ideal suspension travel, but now I'm pretty confident they won't make much contact if at all.
(Note: I adjusted the coilovers differently after that for different wheels and tires)



3) Photo of the fitment on the ground. Basically flush, but IMO a bit too aggressive.



Note that RT660's are very wide.
It's possible that other 245/40R17 tires on 17x9 +45 will fit perfectly fine.

Also worth mentioning that I didn't have time toe check inner clearance, which might also be a concern as we get into the higher numerical offsets.

[Petah78]

Originally Posted by timurrrr

Tried Falken RT660 245/40R17 on Enkei RPF1 17x9 +45.
I have Verus RLCA and temporarily have coilovers from a gen1 car.
~1" drop vs stock, and -2.5º camber at ride height (so ~0.5º additional camber compared to stock arms?).

Just curious what difference will Gen 1 coilovers make? I think most makes are not releasing a different set as suspension is interchangeable between all MY?

Thanks.

[timurrrr]

Originally Posted by Petah78

Just curious what difference will Gen 1 coilovers make? I think most makes are not releasing a different set as suspension is interchangeable between all MY?

I know multiple coilover makers that are working hard on gen2 updates right now.

Gen2 has different rear arms, and stiffer body.
Even with gen1 rear arms, the stiffer body means you may want to soften some things up a bit (e.g. "fast bump damping") and/or add increase anti-NVH measures.
It took me 5 minutes after installing gen1 coilovers and wheels/tires to notice higher NVH than it was on the gen1 car with the same coilovers and wheels/tires.

[DocWalt]

I think many Gen 1 coilovers were done poorly even for first gens, so no surprise they're updating

I have *zero* clearance issues with 245/40R17 Yokohama A052s on 17x9 ET45, even compressed further than what timurrrr showed and -2.2 rear camber (even more clearance now with -2.6 rear camber. YMMV with tires, the RT660s run stupid wide

[Krokodil]

Originally Posted by DocWalt

I think many Gen 1 coilovers were done poorly even for first gens, so no surprise they're updating

I have *zero* clearance issues with 245/40R17 Yokohama A052s on 17x9 ET45, even compressed further than what timurrrr showed and -2.2 rear camber (even more clearance now with -2.6 rear camber. YMMV with tires, the RT660s run stupid wide

Zero clearance issues with 245/40R17 Yokohama A052s on 17x9 ET45 on coilovers?
I think about trying same tire on 17x9 et45 with stock shocks/springs.
In front: peddlers top hat, combination of camber bolts, Apr studs, 10 mm spacer.
Rear: upper control arms.
Am I being realistic?
Would it be better to use different offset or different spacer?

[DocWalt]

Originally Posted by Krokodil

Zero clearance issues with 245/40R17 Yokohama A052s on 17x9 ET45 on coilovers?
I think about trying same tire on 17x9 et45 with stock shocks/springs.
In front: peddlers top hat, combination of camber bolts, Apr studs, 10 mm spacer.
Rear: upper control arms.
Am I being realistic?
Would it be better to use different offset or different spacer?

Yes, with coilovers.

Those mods should make them fit with stock shocks/springs, the biggest issue will be front spring perch clearance.

[OkieSnuffBox]

Originally Posted by timurrrr

I know multiple coilover makers that are working hard on gen2 updates right now.

Gen2 has different rear arms, and stiffer body.
Even with gen1 rear arms, the stiffer body means you may want to soften some things up a bit (e.g. "fast bump damping") and/or add increase anti-NVH measures.
It took me 5 minutes after installing gen1 coilovers and wheels/tires to notice higher NVH than it was on the gen1 car with the same coilovers and wheels/tires.

Which ones specifically?

I'm curious because I have a custom set of 8th gen FA500s being made now and when we asked if there were going to be any updates to their offerings for the 2nd gen their verbatim response was:

"We did testing on the new BRZ and found that our original setup still worked best. So there were no changes made on the new GR86/BRZ compared to the old FRS/BRZ."

[Krokodil]

Originally Posted by DocWalt

Yes, with coilovers.

Those mods should make them fit with stock shocks/springs, the biggest issue will be front spring perch clearance.

Yeah. It is already super tight at perch with 17x8 45mm and no spacer.
So 10mm spacer is less than 1/2” that 9in wheel will grow inboard relatively to 8in wheel.
Probably will have to dial back some of precious knuckle camber or to try even thicker spacer.

[Ogt]

Originally Posted by Krokodil

Zero clearance issues with 245/40R17 Yokohama A052s on 17x9 ET45 on coilovers?
I think about trying same tire on 17x9 et45 with stock shocks/springs.
In front: peddlers top hat, combination of camber bolts, Apr studs, 10 mm spacer.
Rear: upper control arms.
Am I being realistic?
Would it be better to use different offset or different spacer?

For what it’s worth, 100% stock I run 17x9 +45 with the 245/40 yok a052 front and rear no issues.

[Xed32]

18x8.5 +40 Superspeed Rf06RR with Advan Apex 245/35. Stock suspension. 5mm spacer up front allows my -3.2 camber up front ( pedders+camber bolts) without any issues.

[DarkSunrise]

Apex ARC-8 wheels from my 1st gen. 17x9 +42. Tires are 235/40/17 gtradial sx2. Stock suspension/alignment. I think this might be a good 2nd gen tire/wheel combo with coilovers and typical track camber. Right now there’s a little bit of poke, but not bad. Looks better than I was expecting actually. I was going to sell these but now I’m not sure…

[AK2112]

Love a bright silver wheel on a bright red car. Looks rad.