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Premium Member
07 Forester XT
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Discussion Starter #1
In my never ending quest to cram the widest tires under the Forester's fenders, today I worked on my latest project. I've been slowly moving up with wider wheels, 17x8.5 last year and 17x9 this year with both 245 and 255 rubber (auto-x / track setups). Today's project involved test fitting some even wider rubber on my 17x9's . I picked up a pair of 275/40/17 Kumho V710 tires which a friend was running on his Mustang GT. Its cheapest to test fit a free set of used, burnt up tires than to risk buying a new set for $1k. Since I was only able to score 2 tires I couldn't take a test drive and do anything more than a static test fit.

I had two of them mounted on my wheels as my current V710's are spent and need replacing anyway. My suspension setup includes coilovers with camber plates along with camber bolts front and rear. I'll start by saying there's no way this would fit with an OEM strut body, the lower perch is way too wide. The use of camber bolts allows me to pull the tire away from the strut body which is already thinner on a coilover. The camber plates then allow me to dial negative camber back into the alignment.

Step one, try and mount the tires, see if they even allow the wheel to sit flat on the disc





Success ! The tires clear enough that I can properly seat the wheels onto the car, I really wasn't sure how well it would fit.

Step 2, check to see if the front tire can fully turn without rubbing on bodywork. Odds are I won't ever get full lock on an autox course but its good to know if its making contact and to what extent. Looked just fine to me.





Step 3, verify clearance between the tire and the strut body. Fenders I can roll, rubbing on the strut you can't without adding a spacer which I'd rather not do. Note to self, its always too dark on the inboard side of the tire to get decent pics. I stuffed a trouble light back there to help illuminate the shots for the camera. Even getting underneath the car its hard to tell if its rubbing or not. I needed to use the camera to see if there was any touching. There just isn't the room to get your head behind the tire and from underneath I can't get a good perspective on the collars.

Front:










Its hard to tell, I can't be 100% but it looks like it either barely clears , or it barely touches. Those shadows create dark areas I can't see into. Using your fingers to feel the gap doesn't work at all, its way too close to get anythign besides a sheet of paper in there (in hindsight I should have tried a paperclip) Above are the shots from the rear side of the front strut. Below are shots from the front.

The good news is that I document all my suspension settings. I know that I set my camber bolts to full negative. This means I will have the ability to set the camber bolts to full positive which will pull the tire further away from the strut body. Then I'll use my camber plates to return the tire to a negative setting. Looks like this side will work just fine.











Rear:

Tire clears the strut body no problem, can't tell from this angle if its touching the collar.



The view from above, there's a gap and plenty of it. Looks like this will work back here as well.








Side views, yes the tires now protrude far out.

Front tire:





Compared to the 245 RE01R's on the passenger side, you can really see how much a 275 sticks out.




Rear tire: I had some rubbing on the rear fender with the both the 245's and the 255's this summer. On the street its fine but on the track with hard cornering its making contact with the fender. Looks like I'm going to have to roll the fenders comes next spring but if it allow me to run a set of 275's then so much the better.






245/45/17 RE01R compared to 275/40/17 V710. You can really see a difference in width. The V710 is as wide as the mud flaps.




Conclusion: It appears with some camber adjustment and a little fender rolling in the rear I should be able to safely run a set of 275/40/17's next year without resorting to a crazy low offset or swapping to 5x114.3 hubs which is an expensive project in itself. While my track tires still have lots of rubber on them, the autox set is finished and I'll need a new set for next summer. At the moment I am undecided between buying V710's or the new Toyo R888 SG super sticky compound they are releasing next year. I'm going to wait for pricing to see which way I will go.
 

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Ol' Timer
2006 WRX Spec-C 6MT
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6,091 Posts
^^Track day rubber, no need to drive them on the streets.

Wow. That's a wide arse tire. Looks like you have some issues to resolve in the front, and maybe some in the rear. Under hard cornering forces the tire might deflect some and rub more than it does now.
Honestly, IMO lower offset wheels would be perfect. Just 5mm is all you need to run that size without problems or concerns about rubbing the strut bodies. Sure, you'll have more issues with the fenders, but ramping up damping and rolling the fender would easily cure that.
 

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none none
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9,011 Posts
Couldn't you lift up the car slightly to get a bit more clearance to the collars?

Just curious but have you ever had any issues with the tire rubbing on the plastic cover over the fuel filler tube in the pass side rear wheel well? My wheel clear the fender fine, but it tucks into the wheel well and rubs on the plastic cover on long dips in the road (or when it comes crashing down after a set of train tracks you didn't notice doh!)
 

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Premium Member
07 Forester XT
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6,792 Posts
Discussion Starter #5
I'm willing to bet with 4 slicks mounted I'd have a hard time moving in the snow. It would be slightly better than driving on ice.

^^Track day rubber, no need to drive them on the streets.

Wow. That's a wide arse tire. Looks like you have some issues to resolve in the front, and maybe some in the rear. Under hard cornering forces the tire might deflect some and rub more than it does now.
Honestly, IMO lower offset wheels would be perfect. Just 5mm is all you need to run that size without problems or concerns about rubbing the strut bodies. Sure, you'll have more issues with the fenders, but ramping up damping and rolling the fender would easily cure that.
I'm thinking all the tire deflection is going to occur on the bottom since that's where all the weight is. None the less I am considering installing a second set of camber bolts front/rear to help pull the tire that much more from the collars. Even with my 255's the tires are nearly as close and there's no signs of rubbing on the inside of the tire.




Couldn't you lift up the car slightly to get a bit more clearance to the collars?

Just curious but have you ever had any issues with the tire rubbing on the plastic cover over the fuel filler tube in the pass side rear wheel well? My wheel clear the fender fine, but it tucks into the wheel well and rubs on the plastic cover on long dips in the road (or when it comes crashing down after a set of train tracks you didn't notice doh!)
Yes, but by raising the ride height now you've changed a whole bunch of other factors which I'd need to address. I'd probably have to raise a full inch which is a ton. I have it set for STi ride height as is. It would make more sense to increase the spring rates however I'm happy with the handling AND the daily driver useability so I don't want to mess with that and make it worse. I recall you mentioning the fuel tube earlier. I did look and there's no rub marks back there at all.
 

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02 Foz 4eat
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5,548 Posts
Didn't RAAM get a 275 on his Foz? That's a wide *** tire. Does that much more rubber make a big difference over say a 255? Probably for the competitive driver, but probably not for an amatuer, right?
 

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Premium Member
None FXT i exploded 4eat one good 4eat
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809 Posts

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Ol' Timer
2006 WRX Spec-C 6MT
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6,091 Posts

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Premium Member
07 Forester XT
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6,792 Posts
Discussion Starter #14
Didn't RAAM get a 275 on his Foz? That's a wide *** tire. Does that much more rubber make a big difference over say a 255? Probably for the competitive driver, but probably not for an amatuer, right?

He had wider, 305 IIRC. However he did it by going 5x114.3 which is hella expensive and around a 25-30 offset. I'm trying to do it at a reasonable (to me) cost and a setup that isn't too hard on the bearings. I should see a big jump in grip , its simular to going from a 205 to a 225 tire.


Side note, I had 205/55/16's when I first tracked my White XT. I was melting ribbons of rubber off like it was a candle.


They are his "tester" tires, so it doesn't matter if they are wore out.
Someone's reading my entire posts :raspberry: Yes, these are rather worn out. Coming off a Mustang you can rest assured they were given the royal fairwell in a cloud of smoke.

Now today I was able to play around a bit with camber. I was supposed to swap suspension but that didn't quite work out. What I was able to do was to play with the camber bolts in the rear. The bolt was set to max negative camber (pulling the wheel in towards the strut). I loosened it off and set it to positive camber and voila, tons of room. You could see the tire move a good 1-1.5 inches away from the collar as I spun the camber bolt around.

There's more gap now than there was with the 255's which is good. Next I'll play with the fronts, hopefully with simular results.

Negative camber:


Positive camber:



Negative camber:



Positive camber:
 

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2006 XT
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675 Posts
Yup the spacer will give you the needed space, but then the marbles will stick on your mirrors:biggrin:. Ya gonna do the slicks for solo, DS, ESP or SM? And what no SS brake lines... with your track record (no pun intended), I'd consider that basic table stakes. imho
 

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Premium Member
07 Forester XT
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6,792 Posts
Discussion Starter #18
I could probably live with 3mm spacers, its not too much out but I really want to avoid it if possible.

As for SS lines I'm on the fence on that mod. There's too many pro/con arguments on what they actually do, if they feel better or work better. So far, I've been pumping my money into mods I know will benefit me for sure. Upgrading to DOT 4 , bleed fluid regularly, race pads. This season I haven't had any scary brake moments with fade, engagement or modulation. Its not that I wouldn't do them, I haven't felt the need (excuse that pun) to install a set.

With regards to classification, its a little different than SCCA here in Canada. They use SCCA rules and modify some parts. Essentially my car starts off in D class and every 30 points you move up a class to a max of A class. I'm currently in B.
 

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04 FXT
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41 Posts
good thread!

any update on rolling the fenders?

i have an 05 sti i fit 275's on for autox but it was A LOT easier; all i needed was a 5mm spacer in the rear 629.photobucket.com/albums/uu12/meathooker/sti275.jpg

looking to get a fxt and hoping to do the same; looks like it is possible with a bit more work
 
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