Hey everyone,

I'm looking to sell my 19" wheels and get a set of 18". Personal preference, but I just like 18" on a 996tt over 19".

My current setup is:
Front: 19x8.5 with 49 offset Pzero 245/35-19
Rear: 19x110J with 40 offset Pzero 295/30-19

After installing H&R springs and Bilstein B8 struts I have some rubbing. I rolled my fenders (I can probably roll them some more one of these days) and was able to get rid of 95% of the rubbing.

If I get a new set of wheels, I will want to make sure I don't need to worry about rubbing at all. Ideally, I was thinking about doing 9 in front ad 12 in rear but I might have the same issues with rubbing, plus it is an overkill on a street only car. So I think I will settle for 8" front and 11" rear to keep stock tire sizes.

So what offsets should I go for a nice look and have zero issues with rubbing? Should I still do 40 offset rear and about 45 offset front? Since the wheels will be 1" smaller, the I should have about a 1/2 inch more room now around the fender?

Any advice, recommendations?

Thanks

Current setup

 

i have virtually the same setup and i went back to gt2 sizes from a 9x12 in front. the 40 offset front/rear was good for the 9"..


but ultimately i prefer the 8.5 ( 40 ) in front as there is less plowing in the corners for me ( if in fact i could even discern that 1/2 in difference?! ). the 9 would be better on the track perhaps.

but i'd stay with the 12" in rear if it were me, ( you'll better appreciate that extra inch running a 12" ) and stay in fact with the gt2 setup 40 and 45 offset and if your fenders are properly rolled you shouldn't rub, though i did eat thru my rear liner but that was from bouncing. if you stay on the ground it should be fine.

lots of others will have possibly more experience with varieties of sizes and what not, but you will not go wrong with the gt2 sizing..

or alternately just ask pwdr.. since he's tried every combo there is.

 

Thanks '02996ttx50, as always. Yeah, before I bug pwdr via pm, I hope he will chime in and well as others

So GT2 wheels specs are:
front: 8.5x18 ET 40
rear: 12x18 ET 45
tyres front: 235/40 ZR 18
tyres rear: 315/30 ZR 18

That pushes out the rears about 8mm more. I'm very worried that extra 1/4" will make the rear rub even more.

Also from what I read, pzero tires are much wider sidewalls then most others in that same side. I'm guessing a none pzero 295 tire would not rub with my current setup.

 

i don't sense ( or have measured ) any difference btw say a ps2 and a p zero ( the only types i've run ) and i haven't ever run the stock size in the rear. even with twists i ran a 315/30..so i cannot say. but the 295 rear would i suppose mitigate most situations for rubbing you the wrong way. as i understand it, we only roll the fenders to accommodate the larger tire/wheel combo.

i'm sure others will add their experiences also. given you've already begun on the rolling/liners? i'd finish up to accommodate the 12" properly. if it were me.

 

OEM GT2 sizes and ETs are a safe bet assuming you wanna stick with the OEM GT2 235/315 tire sizes. These are good for AWD. 245/40 and 315/30 is even better. As such I recommend 18x9x12 as 8.5s are a bit on the skinny side for 245s. I like 18x9 et 45 and 18x12 et45. If fenders are rolled you can go 18x12 et40. Here a pic of 18x9 et47 and 18x12 et 40 with 240/40 and 315/35 tires. These are rather tall at 25.7" and 26.4" with plenty of clearance no rubbing. Rears are full 1" taller than stock size.

[url=https://flic.kr/p/B3mp48]

 

Thanks pwdr. So based on your recommendations, it seems the offsets are more aggressive in the rear by about 8mm.... won't this make my rubbing worse or will going down to 18" offset that?

Because of my suspension setup, I would bet that my struts compress a bit more then yours which causes me to rub fender/liner. You can see by my pic that h&r springs are realy not giving me much gap between fender and top of tire.

 

I'm not sure where you are getting the 8mm calculation. 18s or 19s won't make a difference if you keep tire diameters the same. Wheel width really doesn't matter much either because it's your tires that rub the liner/body/whatever, not your wheel. A wider wheel simply stretches the tire a little more at the bead. An 11, 12, or 13" wheel of the same ET will have the tire centered exactly the same with the only difference being the stretch of the bead. Yes, that will impact clearances slightly under heavy compression but usually its the edge of the tire that causes rubbing not the side by the wheel. Keep in mind however that as you add camber in the rear, your outer tire moves in away from the fender. At the same time, the inter part of the tire moves away from the liner near the lower boost hose. As you reduce camber, your clearances are reduced in both areas. In other words, the less camber you want to run, the tighter your clearances become. In the rear, I run -2.4º camber. In the front I run -3.4º.

If you are trying to fit the largest possible wheel tire combo or optimize your fitment, do the following to check you clearances and determine a perfect ET. Put the car up on 4 jackstands and remove the wheels. In the rear you need to disconnect the lower shock mount from the wheel carrier and disconnect the sway bar on both sides. Put the wheel back on and place a jack under it. You can then fully jack the wheel up compressing it up into the wheel well and get and idea of the contact/interference areas. You can also rub some chalk on the edges of the tire and as you compress it into the wheel well the chalk will transfer to the contact areas in the wheel well. 12" rear will work at ET40-45. The front is a no brainer with 235-245 tires with 9" at ET45. Check clearance lock to lock.

Rolling the rear fenders tightly is easy to do and opens up a lot of room. The one area that gets overlooked is the end of the fender near the plastic bumper cover. This is a clearance problem under heavy compression. I grind this area away with a carbide bit gaining about 1/4" there. You can see where I did this and than resealed it with paint. This is not normally necessary but mandatory when running 335 at very low ride heights. Also note how tightly my fender is rolled and how I cut away the plastic lip of the bumper cover at an angle making more room for the tire under heavy compression. Doing all this allows me to fit 18x13s with a 26" tall 335 tire at 1/2" below GT2 ride height.

Hope this helps...

[url=https://flic.kr/p/FzqHSV]

 

Thanks for the write up. Greatly appreciate you taking your time to do so.

The 8mm difference I mention was going from my current 19x11 e40 wheel to a 18x12 e45 wheel. That pushes the rear wheel about 8mm out more towards the outside right? Which I'm worried would cause more rubbing.

But going from a 295/30r19 tire down to a 315/30r18, brings the tire diameter down about 1/2". So that extra space gained from going with 18" might be enough to eliminate the rubbing I currently have with 19".

I'm not trying to fit the biggest wheel/tire possible, I just don't want to rub anymore if I get new wheels and still keep that aggressive look I currently have.

My buddy already recommended the chalk idea so I will try that next to find where I'm rubbing in the rear and front. My guess is that I'm hitting wheel liners now, buy I still have some more room to roll the fender. I'm no where close to have them rolled like yours.

I didn't think my current setup was that aggressive and I'm just surprised I have so much rubbing.

BTW, it is funny you mentioned trimming the bumper by the screw. I just did that last week

Also, are you running GT2 liners or Turbo ones? Can Turbo ones be modified at all to give more room if I'm rubbing liners during compression?

 

freakin genius writuep that will stand the test of time. sticky that.

 

I think Pwdrhound and I have the most modded wheel wells I've seen. Everything he said is spot on.

I was able to fit 255/35/19 on 19x9+40 and a 325/30/19 19x12+40. It was a lot of work to do right though. If I did it again I'd go 275/30/19 front instead though on a 9.5 wheel

 

 

What tires come in a 315/35? The best setup I could find are

315/30/18 and 235 or 245/40/18 but there are at least a lot of good tires in those sizes. Tempted to drop down to 18s so I can run the RT615K