Ordering custom Forgestar wheels -- is this the right offset?

[guarnibl]

Hey guys,

My goal is to be able to run the widest possible front tire and still be able to clear a front and rear coilover setup.

I was hoping to be able to run 295's up front (295/30ZR19), and 305's (or 325's) out back (325/30ZR19 or 305/30ZR19). This retains the factory 30mm difference on 325's (or lowers it to only 10mm) between front/rear for street, and allows me to run 295's front/back for a square setup should I decide.

Paul @ Howey Industries set me up with Forgestar CF5's in Matte Black with 19x10 +38 and 19x11 +53. He said this will keep the wheels just inside the fender.

Does this sound like the correct offset I need to run? If not, why, and what would I need to change? He said he does hundreds of Mustang setups a year, so I'm pretty sure he's right -- but rather be safe than out $1600.

Planning on running Toyo Proxes R888's front/rear.

I haven't purchased an additional suspension components at this time for the car excluding some rear frpp relocation brackets for the frpp solid billet control arms that I bought. I'm completely open to whatever suspension coil over kit I need to run in order to fit this setup. Was hoping to avoid going SLA due to cost....

Thanks guys!

 

[Boss3oh2]

You'll have a little stretch with 305's on the 19x11 and the 295's will bulge a little bit.

 

[IamRacerX]

Not sure I have heard anyone running a 295 up front. 325 out back I have seen. The offsets will have to be perfect for them to work with hitting anything as those sizes represent the absolute largest tires you can fit. While you offsets sound like they are about right, I can't say that with any certainty with those tires. Goodluck and keep us posted.

 

[cp85gt]

I am running about what you are looking for. I have 19 x 10 Forgestar F14 +42 with 295 30 19 in front and 19 x 11 +55 with 305 30 19 in back. I did have to make a small .062 aluminum spacer in front so their would be the minimum 3mm of caliper clearance. I also have -1.8 camber in front. I am lowered on AST's about 3/4" in front and 1-5/8" in back with no rubbing on an autocross course. The front and rear is mostly flush with the rear Michelin PSS rim protector sticking out slightly.

 

[guarnibl]

You'll have a little stretch with 305's on the 19x11 and the 295's will bulge a little bit.

Toyo recommends a 19x11 for perfect fitment on 305/30ZR19 on their proxes r888. 295's are pushing it a bit (11.2" tread width vs 11" wide wheel). I believe if I run Griggs I can run 305's in each corner.

Not sure I have heard anyone running a 295 up front. 325 out back I have seen. The offsets will have to be perfect for them to work with hitting anything as those sizes represent the absolute largest tires you can fit. While you offsets sound like they are about right, I can't say that with any certainty with those tires. Goodluck and keep us posted.

Griggs and Voshlag both run crazy wide up front but they're heavily modified, which I'm trying to avoid Us normal folk -- I agree, I've never personally seen it. I've heard of it, just never with offsets mentioned until this guy below me here.

I am running about what you are looking for. I have 19 x 10 Forgestar F14 +42 with 295 30 19 in front and 19 x 11 +55 with 305 30 19 in back. I did have to make a small .062 aluminum spacer in front so their would be the minimum 3mm of caliper clearance. I also have -1.8 camber in front. I am lowered on AST's about 3/4" in front and 1-5/8" in back with no rubbing on an autocross course. The front and rear is mostly flush with the rear Michelin PSS rim protector sticking out slightly.

Great to hear. Are you clearing coilovers?

So I'm still slightly confused on back spacing. +42mm I assumed would rub, but 38 would clear on a 19x10. Is this because +38mm pushes the wheel out more from the inside of the vehicle? Or is it the other way around? I assume I'm correct in that the less positive I go -- the more likely the wheel will stick out past the fender (thus giving me problems with uptravel).

 

[cp85gt]

The smaller the offset the less backspace so a +38 offset would have less backspace than a +42 offset, thus stick further out. With the small spacer in the front I'm effectively between a +40 and +41 offset. With a 295 in front I would not go less than a +40 offset as even with extra camber added I'm close to flush with the fender. The AST's are an adjustable coilover and the 295's fit without rubbing. I also have a watts link so I have a bit better axle control. Another thing to consider, since things happen, and you might need to sell the undamaged front wheels, a +42 offset 19 x 10 wheel fits I the rear, while a +38 19 x 10 wheel will poke out a bit. 1 mm equals about .039" so keep that into account when trying to figure out what backspace you want.

 

[MeanGreenBoss]

I went with 19x11 +55 Forgestar CF5's from Howey Industries on the rear of mine. With 305/30ZR19 Michelin PSS tires, there is a very slight poke since the MPSS 30-series side wall for this size flares out a bit. If I'd have known this, I would've either gone with a +56 offset or gone with the 305/35 series with a more conventional sidewall. BTW, there's at least an inch clearance with the rear shock, so there's room to run more backspacing. Also, you're going to need an adjustable panhard bar if you don't have one already.

 

[Jabooh1]

I have 19x11 rear with +53 and a 305/30. It fits fine. I would do 20's though as 305/30 is a short tire and looks weird to me.

 

[guarnibl]

The smaller the offset the less backspace so a +38 offset would have less backspace than a +42 offset, thus stick further out. With the small spacer in the front I'm effectively between a +40 and +41 offset. With a 295 in front I would not go less than a +40 offset as even with extra camber added I'm close to flush with the fender. The AST's are an adjustable coilover and the 295's fit without rubbing. I also have a watts link so I have a bit better axle control. Another thing to consider, since things happen, and you might need to sell the undamaged front wheels, a +42 offset 19 x 10 wheel fits I the rear, while a +38 19 x 10 wheel will poke out a bit. 1 mm equals about .039" so keep that into account when trying to figure out what backspace you want.

I figured a 295 would fit just with minor trimming when on the FRPP 1/2" drop P springs. But if we end up sticking out -- which by the way, I assume you say it's sticking out because the 295 tire bulges more on a 19x10 than a 275 tire? Don't see the point in running tread I can't put to the ground? I also need to clear 15" rotors, which these wheels do, but I think with a +42mm I'll hit the calipers. Pretty sure with 15" rotors and 6 piston brembo calipers I need to run +38mm in order to clear. So if I run a +42mm, I'll need to run a +5mm spacer to clear the caliper.

I don't think I'm getting any additional tread up front and down to the ground with a 295 over 275...so what's the point of running larger than 275? Also, I don't think a +42mm would clear 15" rotors w/ 6 piston calipers. Tread width on a 275/30ZR19 is 10.2" -- there's no point in running a wider tire, you just end up with a bulge.

So I'm thinking :
Front: PSS 275/30ZR19 -- 10.2" tread width.
Rear: R888 295/30ZR19 out back -- 11.1" tread width or 305/30ZR19 for 11.5" tread width.

As close to square setup being able to put all the tread to the pavement (and rear tire would be really really stretched but it's acceptable limits according to Michelin) would be 275/30ZR19 (10.2" tread width) and a 295/30ZR19 (11.1" tread width).

Am I misunderstanding tread width and getting that tread to the ground?

 

[cp85gt]

There are several 18 x 10 wheels that clear the 15" Brembos ( BBS, PFO1, Team Dynamics), so you don't have to run 19" wheels if you don't want to. I went with the sizes I did to keep a stagger while keeping the front rear tire diameters about the same. The 30 series tires are about 1" shorter than the stock tire sizes. The 295 Michelins are a little pinched on a 10" wheel but the tire shoulder is still fairly square. In terms of "getting the tread to the ground" if the tire is way to wide for the rim, like a 325 on a 10" wide wheel, then you can have problems with the steering feeling loose and squirmy. A 275 tire would feel more responsive to drive on but these heavy mustangs need all the tire they can get if you plan to autocross and open track. If I get serious and get a dedicated set of track wheels and tires I would get a set of 18 x 10 wheels and run some Continental 305 scrub slicks on them for cheap, or some new BFG Rivals in a 295 35 18 size.

 

[guarnibl]

There are several 18 x 10 wheels that clear the 15" Brembos ( BBS, PFO1, Team Dynamics), so you don't have to run 19" wheels if you don't want to. I went with the sizes I did to keep a stagger while keeping the front rear tire diameters about the same. The 30 series tires are about 1" shorter than the stock tire sizes. The 295 Michelins are a little pinched on a 10" wheel but the tire shoulder is still fairly square. In terms of "getting the tread to the ground" if the tire is way to wide for the rim, like a 325 on a 10" wide wheel, then you can have problems with the steering feeling loose and squirmy. A 275 tire would feel more responsive to drive on but these heavy mustangs need all the tire they can get if you plan to autocross and open track. If I get serious and get a dedicated set of track wheels and tires I would get a set of 18 x 10 wheels and run some Continental 305 scrub slicks on them for cheap, or some new BFG Rivals in a 295 35 18 size.

Yeah that sounds right. I'm misunderstanding tread width as well -- a 19x10 wheel will actually put down up to 11" of tread width. Paul thankfully let me know that as I was horribly confused when trying to figure out why people were evening bothering to run larger than 275 on a 10" wheel.

For what it's worth, the Michelin's in 295/30ZR19 offer 11.5" of tread width, while the Toyo R888's in the same size only offer 11.2" -- given the next size down is a 265/30ZR19, I think I'm better off with a 295/30ZR19. I'm very set on the R888's -- I don't want to run a PSS up front and an R888 out back as it sounds like that will negatively impact the handling of the vehicle to run mismatched tires.

I can't clear the GT500 calipers on any additional backspacing beyond a +38, so anything more is out of the question. And I'm not looking to go out and spend $4500 on a brake kit at the moment (I think I can get away just fine with the GT500 kit, and perhaps add the floating rotors in the future along with the ducts). I'm not super comfortable running spacers either, but finding anything less than 5mm is nearly impossible (as you said -- I think you had to make your own.. which can change the balance of everything, and it's just not something I want to do). So we're just going to go wild wild west and try the +38 19x10 -- worst case I'm out $800, which I can live with. Though Paul seemed confident with minor trim work and possibly rolling the fenders, that I would clear just fine.

So what I end up with (w/ minor trim work):

Front: 19x10 +38 on Toyo Proxes R888 295/30ZR19.
Rear: 19x11 +53 on Toyo Proxes R888 305/30ZR19.

All clearing the large front Brembo kit (15" rotors, 6 piston calipers).

Do these forgestars work w/ TPMS? Do I need new lug nuts or anything?

 

[fast4v]

This is what a 20X11+53 offset looks like with a 305/30.

 

[guarnibl]

This is what a 20X11+53 offset looks like with a 305/30.

Nice ride

Yeah, I'm not too terribly concerned about the look. Only to make sure it doesn't break stuff on the track.

 

[fast4v]

Nice ride

Yeah, I'm not too terribly concerned about the look. Only to make sure it doesn't break stuff on the track.

LOL...no worries, bad angle just wanted to show you its flush with the fender and also running KW variant 3 coil overs with no issues

 

[guarnibl]

LOL...no worries, bad angle just wanted to show you its flush with the fender and also running KW variant 3 coil overs with no issues

Rock on! It's a bad ass looking !!

How do you like the KW variant 3 coil overs ... what wheel/tire are you running front?

 

[Grant808]

I think you've got the right offset for the front as long as you can run some camber, and anything between +52-55 should work in the back.

 

[guarnibl]

I think you've got the right offset for the front as long as you can run some camber, and anything between +52-55 should work in the back.

It'll be close I think ya.. should be able to run some camber though and clear it.. maybe have to trim a bit. But a 30 is a shorter tire.. so we'll see.

 

[IamRacerX]

Those tires are short too... You are going to be changing the gearing shorter with them.

 

[guarnibl]

Those tires are short too... You are going to be changing the gearing shorter with them.

Yep. I was hoping to throw in a built TR6060 or Magnum. We'll see. Not sure the TR6060 will bolt right up without a lot of work. The reason I'm leaning towards the TR6060 was my understanding the first gear tops out at ~62 mph where the Magnum I would be similar to where I'm at now.

Right now I'm looking at installing a new clutch to fix the sticky clutch pedal issue (unless there is a cheaper way?) and I don't want to do that twice. Rather just throw a completely new transmission into it...

 

[IamRacerX]

Niether trans is comparable gear ratio-wise to the M82... afterall the m82 is 1to1 in 5th. Its much closer ratios. I believe the magnum comes in a close ratio version, but its still not as close as the m82. As far as doing 62 in 1st... that is about what second does in the m82 with stock rear... from a dead stop I dont think there is enough off idle grunt for that to be used as a regular 1st ratio imo... but you can play with ratios via the rear ratio.