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Wider Wheels and Tires on a Staggered Setup

Dark Horse

2012 BOSS 302 LS 541
I'm looking to purchase another set of wheels and tires for my Laguna Seca, I want to save my factory ones for track days. Does anyone have any experience with going wider in both the front and back on a 19" staggered setup? Specifically, has anyone tried a 9.5" front and a 11" back? I do intend to lower the car in the near future similar to what Boss3o2 https://trackmustangsonline.com/boss-302-technical-forum/installed-some-new-mods-on-my-boss/ has posted previously. What offsets are necessary and any other issues that may keep me in the stock widths? I definitely appreciate the insights.
 
Unless you go uber expensive Forgestar's will be your best bet. Check Element Wheel for prices and also look at the CF5's. They also come in 9.5 and 11.0 like you want. They know the proper offsets.

http://www.elementwheels.com/proddetail.asp?prod=fs-f14gm1990fs-f14gm1910
 

drano38

Wayne
1,130
318
Dark Horse,
Another idea is use stock wheels for street, and buy new (and lighter) track wheels.
Several choices out there, but Enkei PF01 are great for track days.
Cloud9 has posted he used this.
Front 18 x 9.5 35mm offset, 285/35/18
Rear 18 x 10.5 38mm offset, 305/35/18
Tires were Nitto 555RII. I know he's trying different tires this year.

I don't know your overall goals, but those stock wheels way a ton. Enkei are about 21 lb each. Better for track days, and not as heavy to install/remove/stack up/put on tire rack, etc.

I've got 2 sets of PF01, 18x9.5 and run square with Nitto NT-05, 275/40/18.
Just some more ideas for you to consider.
 
Sorry to revive an old thread guys I just had a curious question and went searching when I stumbled across this. By now I'm sure you guys have heard about the new Z/28 and it's massive 305/30ZR Pirelli Tires. I guess my question is would the Boss benefit from wider tires on the track and if so, what are the widest tires you are able to put on the back and the front? Would you need new rims to accomodate these wider tires in the back as well? Oh and I do apologize for the misleading nature of the topic name, I am referring to the Z/28's square setup with those tires on all four corners.

Just curious about the answers since you guys are very knowledgeable on track topics.
 
El Jefe 302 said:
Sorry to revive an old thread guys I just had a curious question and went searching when I stumbled across this. By now I'm sure you guys have heard about the new Z/28 and it's massive 305/30ZR Pirelli Tires. I guess my question is would the Boss benefit from wider tires on the track and if so, what are the widest tires you are able to put on the back and the front? Would you need new rims to accomodate these wider tires in the back as well? Oh and I do apologize for the misleading nature of the topic name, I am referring to the Z/28's square setup with those tires on all four corners.

Just curious about the answers since you guys are very knowledgeable on track topics.

I would think a square would be the only true way to setup track rims and tires since you would have more grip on all 4 corners. That being said I have read that square will either require you to be very good at modulating the throttle to curb over steer, or switch the a stiffer front sway bar. I also believe I read somewhere that Vorshlag has used 305 square setups, and I think also Pufferfish has run 305's square at Summit. Don't quote me though as my brain is addled.
 

pufferfish

Supporting Vendor
1,094
66
Maryland
yup, I run 305 wide continental slicks on 18x10's at the track. wish it made good economical sense to run that on the street...looks awesome! but, they would undoubtedly cost too much and probably have an annoying amount of tramline issues (following ruts around).

best size wheel is a 10.5 wide for 305's though. that is probably what the chubby...er, um chevy... is on.
 
The biggest staggered setup I have been able to run on the Boss with stock dampers/springs is on 18 x 9.5 +35mm offset fronts and 18 x 10.5 +38mm rear wheels. I ran Hoosier R6s in 295/30/18 front and 315/30/18 rears at the suggestion of their technical expert. Their spec sheet recommends 10-12" rims for the 295 and 11-12" rims for the 315 but they obviously work great on my rims as I dropped 2.7 seconds off my best lap ever using these sizes. I did use an 1/8" spacer up front but am not 100% sure it was necessary. I have also ground down the front swaybar endlink bolts next to the struts for safety's sake. The rears tires stick out a little, but you could go to the +47mm offset to tuck them in some. There's still quite a bit of room on the inside but you also narrow the "track". Pushing the wheels out increases your lateral grip.

Yes more rubber will make the car faster on the race track whether you run staggered or square. It's undoubtedly a major factor contributing to the Camaro's track test success. It's also the reason the Camaro is so big. The manufacturers are required to "cover the tire" with the fenders to prevent rock chips to other vehicles. To go with that big rubber you have to have a big chassis.

If you do run square on the stock suspension you'll need an adjustable front sway bar set to a stiffer setting, a smaller rear bar, or an adjustable rear bar on a softer setting. The car will oversteer like crazy on a square setup with stock suspension. I tried that on the race track in March 2011 ten days after the Boss started shipping :p
 
Oversteer seems to be the way Puffer likes it since I didn't think he has anything special other then H&R race springs.
 
NFSBOSS said:
He has a GT not a Boss and they are setup differently from the factory.
Yes but the fact remains that it has softer shocks and possibly a 1mm smaller rear sway. Not exactly setup to cope with a square setup.
 

PeteInCT

#LS-378 - So many Porsche's, so little time....
Moderator
2,848
14
Connecticut
Facts, experienced opinion or pontification?

Lets make sure we keep them distinct, especially for those who rely on ths site for reliable insight.

-Pete
 
I'm driving a stock GT/TP with square set up (285 Hoosiers) and have zero problem with throttle oversteer, and it rotates nicely under trailbraking. I don't treat the throttle like a light switch, but I'm not shy with it either.
 
4,824
5,564
FWIW if you use a wider wheel, on the same size tire, that would normally cause that end of the car to be looser. I understand that their will be more contact area with the ground, but you are (artificially) taking away sidewall, making the tire stiffer. Stick with the tire mfg wheel recommendation for the size tire you are running for best results, unless you have to get imaginative because of the rules.
 
Brandon302 said:
I would think a square would be the only true way to setup track rims and tires since you would have more grip on all 4 corners. That being said I have read that square will either require you to be very good at modulating the throttle to curb over steer, or switch the a stiffer front sway bar. I also believe I read somewhere that Vorshlag has used 305 square setups, and I think also Pufferfish has run 305's square at Summit. Don't quote me though as my brain is addled.

We (Vorshlag) are certainly fans of square setups, but we haven't really run the 305. Must be your addled brain! ;D

Although we've run skinnier wheels and tires in the past to be class legal for certain SCCA classes that the S197 is no longer in, these are the wheel and tire combos we recommend today:

18x10 with a 275-295 tire. This is the gold setup. Same offset front and rear. Fits well under the fenders. No issues with rubbing anything. Clears all the stock suspension stuff and all aftermarket parts we have tested. Ultra light wheels and they still fit over the 14" Brembo brakes.

18x11 front and rear with a 295-315 tire. This is the biggest square setup we have that fit under the stock, unmodified fenders. Requires a camber plate to really make it work, and a Watts link to keep the tires off the fender lips in the back, but no other parts are necessary. Can not rotate front to rear.

18x11 front and 18x12 rear with 315 tires. This is the widest wheels we can get under the stock fenders. Requires camber plates, Watts link and a swaybar like the Whiteline rear bar. It's easier to live with if you can remove the bump stop perch in the rear inner fenderwell.

18x12 front and rear with 315 tires. This is the widest you can fit under the stock tub, but requires you to trim the front fenders. This supports the 315 tires better than the 11" wheels. You need all the same mods as the 11&12" setup plus trimmed front fenders.

We've tried running a 335 on the rear, but it rubbed on the inner fenderwell AND the outer fender lip at the same time. If you're willing to flare it, or tub it, you can get the really big tires on there.
 
modernbeat said:
18x11 front and 18x12 rear with 315 tires. This is the widest wheels we can get under the stock fenders. Requires camber plates, Watts link and a swaybar like the Whiteline rear bar. It's easier to live with if you can remove the bump stop perch in the rear inner fenderwell.
18x12 front and rear with 315 tires. This is the widest you can fit under the stock tub, but requires you to trim the front fenders. This supports the 315 tires better than the 11" wheels. You need all the same mods as the 11&12" setup plus trimmed front fenders.

I am considering trying 18x12 rears with 315s, although having trouble finding light race wheels that wide. I have been running Enkei PF01s, but not available larger than 10.5. From what I can see the same is true with the BBS 302S race wheels. Any 12" wheel suggestions?
 
LS110 said:
I am considering trying 18x12 rears with 315s, although having trouble finding light race wheels that wide. I have been running Enkei PF01s, but not available larger than 10.5. From what I can see the same is true with the BBS 302S race wheels. Any 12" wheel suggestions?
Jeff Speer at Hoosier gave me the nod to use the Enkei 10.5s with the 315 R6s and they worked great for me. Are you just trying to increase the contact patch with the wider rim?
 
NFSBOSS said:
Check the Vorshlag site. I believe Forgestar will make them in an 18x12.

Yup. Forgestar will do custom offsets. They're light, too: 18x10 F14 is 22 lb. (guessing 12" width might add a lb or 2). CF5 is about 1lb heavier than the F14.
 

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