This is a setup for track. I wouldn't go through all the effort to have "cool big tires" for the street.

I also know that this is a slightly taller tire (not to mention the normal R-Comp actual vs sidewall width). These tires are intended for road racing. It is advantageous to have a slightly taller tire (Hoosier A7 275s for example) in some scenarios. I'd like to get the car to be able to fit a few different sizes of wide slicks/r-comps.


So the question: Best fix for front rub?
A. Add Caster
B. Chop and hack fender liners

 

For starters as minus mentioned those tires are pretty tall which isnt helping your case.

Im not familiar with the K-mac plates as far as how much additional caster you can achieve but looking at your picture you don't have it on the max caster setting. What you want is to move the top of the strut inward towards the firewall.

The Perrin PSRS is a great piece but its actually going to push your wheel towards the bumper even more. On my car I have the Ciro Design Racing plates along with the Perrin PSRS and my wheel is nice and centered. My tires are a little shorter than yours which is helping; theyre a 285/30 on 18x10.5 +30 with a 18mm spacer. Given that my wheels stick out further than yours which means they would be more prone to rubbing that front portion.

But your issue here is most likely two-fold one being your tall tires and the other being your plates not yielding enough caster.

 

^^^

Best thing is to get you to a race shop for a proper alignment, including adding some positive caster, but not too much that will negatively impact straight line stability

BTW, one site shows that tire dia at 650mm which is tall but not that bad. And the section width is 10.88 compared to my Federals at 10.80 (265/40) or my Nitto NT05's at 10.79 (275/40)

 

For reference (measured the same way) 255/35R18 Hoosier A7 sidewall height was ~60mm vs 265/645R18 Pirelli at ~70mm. So a total change of 20mm in diameter.

What is an acceptable caster range? There aren't any "race-shops" in the area, but I can get a good alignment to my specification.

Also I can't get a PSRS (discontinued) . What can/should I get instead? Is there anything that will more the tire further forward from the bottom?

 

Heres a AX thread on caster. Seems like 5-6 degrees of caster is noted as optimum

https://www.evolutionm.net/forums/mo...autocross.html

 

One thing to note is that added caster at the plate will actually bring the top of the wheel farther back and won't solve your problem. The real solution would be adding it at the bottom via offset bushing in the LCA, because that moves centerline forward.

 

Was about to say this^^


Also, that tire is the same height as a 275/35r18 (25.6"), so it's not too big. It's definitely doable. Find a Perrin PSRS kit, or go with the whiteline KCA400m to add caster and move the tire forward a bit.

 

GOOD CALL RJones. I didn't even think about that.

I have no idea how to track down an old PSRS. Will the Whiteline KCA400m be enough? Are there any other options out there? Custom spherical offset bushings?

 

Wait crap I looked at the picture wrong. So disregard what I said above Rjones is right. I thought I was looking at a picture of the front of your bumper and your lip not the rear and sideskirt. In that case the plate is moving it in the wrong direction and the PSRS is what you need.

IIRC the whiteline piece doesnt add as much caster. There is also a superpro version but I think that is the same story. Supposedly Perrin still makes a PSRS for a subaru that is the same part. I guess the only catch is that it may not include the necessary spacers.

 

On my car, the perring moved the tire too far forward. I had to trim the front of the inner fender liner. That's is of course easier than finding clearance at the rear of the fender well. I wan to say the whiteline does about 1/2 of what the perrin does. So it should work fine. When you look up the whiteline, it will say its for an Evo X, but it still fits the 8/9...

 

Yeah agreed the PSRS without plates up top moves the wheel too far forward. When I run my winter setup stock VIII wheels stock tire size my coilovers come off and the wheel is no longer centered. It didnt rub gets very close but my 255/40 and my 285/30 both would hit.

So in this case where the wheel is rubbing the back not the front, duh Im dumb...thats because of your added caster with the plates. Caster is good dont dial it back but better yet get an offset bushing in the LCA and move it forward some.

Im thrilled that my setup with caster maxxed out at the plates and the PSRS centers it perfectly and yielded more caster than other offset bushings and I believe more caster than any other plates on the market.

And yes, as Letsgetthisdone stated if it fits the X then it fits our cars too. I'd look into sourcing a PSRS, might be worth calling Perrin and getting the scoop on the spacers. I know what they look like but I dont have specific measurement for you so cant help you in that regard.

 

**** just happened to me at an autox event in august. haven't had time but fixing it shortly.
I was running ichiba spacers and studs. I have ARPs now and will torque higher than 85 ft/lbs

I noticed when i drive on spacers and drive hard the wheel loosens up. I'm wondering if the aluminum spacer is expanding and contracting a bit to create loose lug nuts

 

Whatsup James!? I haven't seen you on here in forever...sucks to hear about your incident; you musta been pulling mad g's yo!

For starters I dont care for the bolt on spacers so I think you'll have better luck with the slip ons and some ARP's.

However Im in complete agreement with your last sentence. Im running something like a 17mm spacer and ARP's and I've also had the wheel fall off on me if Im not diligent about re torquing the studs. I believe it has to do with the repeated heat cycles. I torque my studs before an event and halfway through just to be sure. I did a Sat Sun event and forgot to retorque them on Sunday and at one point my wheel started shaking. I was like WTF went checked torque on the studs and they were finger lose. Lets just say I was super lucky but it scared the **** outa me.

And FWIW I've always torqued to 90 ft/lbs. There was a discussion on the proper spec before they stretch and I dont recall exactly what it is but I wouldnt just assume that going tighter is any better.

 

hey dude!

I was running ichiba slip on spacers and ichiba extended studs. So I think you are right. I noticed in the past that it was loosening but I was codriving with a friend and we forgot to check lugs in the middle of the runs so so I'm sure they were loose as I have had them loosen up before. I'm not sure tighter is better because of strength the stud as well.

 

Last summer I had all 5 wheel studs break on the front drivers wheel of my autoX SM Evo 8. These were generic extended studs with ~12mm spacer. I had been running this set-up for a few years, had one or two studs break, but never a whole wheel. At that time I considered upgrading to 14mm or 9/16 wheel stud. It should be a simple drill/hone of the hub. I since sold the car but may be worth considering.