Are 315's possible on the rear of a 03-04 Cobra???

SCT2003

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Anybody running some big "monster meats" out back on their "street" Terminators???

From what I read, with 17" wheels it's possible to run 315's out back???

What's the catch??? What size/type of wheel do you need to use??? Will 315's clear the rest of the suspension and fenders without modification???

Any opinions on the subject???

Thanks...

Later...Dave
 

kasee 03

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Only if they are Nitto DR's, I never believed it myself so I ordered some 275's and after seeing how stock looking the 315's were, I took them.
 

Special Blend

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315's will work on these cars in 17's and 18's. Sometimes spacers are needed as well as either a shaved or the rounded MM IRS bolts.
I run the rounded MM bolts and they are extremely easy to install. I also run a 3/8 hubcentric spacer and all is fine.
I am though probably getting some iforged or CCW 505a's this winter and I will no longer need the spacers because the backspacing will be proper.
 

RED2003COBRA

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I run 315 Nitto DR's on my factory 10th Ann rims. Looks great without much of a wheel bulge. No issues at all with the IRS bolt. I'm happy to kind of get traction in 2nd gear now. 1st still is ugly.

Lance
 

JSpeed

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335 will fit if you run CCW wheels made for it.
 

mblgjr

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You can run 315's with minimal effort.

Easy way out:

Pick your favorite 315 series tire, pick up a pair of AFS replica 10.5" width wheels off ebay in the finish of your choice.

Either run the LFP 3/8" spacers/extended nuts OR call MM for the button head IRS bolts OR grind 1/2 the head off the stock bolt. Pick your poison, any work.

BTW, as stated above; with the proper 11" wheel, 335's will "fit"/clear everything, just be prepared to have some road rash on the rear quarters.
 

BlownSVT2003

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mblgjr said:
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You can run 315's with minimal effort.

Easy way out:

Pick your favorite 315 series tire, pick up a pair of AFS replica 10.5" width wheels off ebay in the finish of your choice.

Either run the LFP 3/8" spacers/extended nuts OR call MM for the button head IRS bolts OR grind 1/2 the head off the stock bolt. Pick your poison, any work.

BTW, as stated above; with the proper 11" wheel, 335's will "fit"/clear everything, just be prepared to have some road rash on the rear quarters.

Sorry for dumb question, but what's MM? website?
 

Wolfhound

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315s on back.

110437.jpg
 

04torchred

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315/35/17 BFG DR will clear with nothing else but 3/8" wheel spacers. I borrowed a buddies 17x10.5 with those tires and they fit on my car no problem. 315's look bad ass too by the way.
 

Top_Fuel

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Here is the short story on 10.5" wheels, wide tires and wheel spacers...

All Cobra replica 10.5" wheels on the market right now have the same offset/backspacing (+27mm offset, 6.9" backspace). I'm talking about the 10.5" wheels sold by AFS, Wheel Replicas, etc. Unfortunately, these wheels were never intended to be used on Mustangs with an independent rear suspension (IRS). This is why you often see a disclaimer with these wheels that says something like "will not fit 1999+ Cobras." Nobody makes a wider-than-stock replica wheel for '03-'04 Cobras that has the proper offset and backspacing...so we're stuck using these wheels. The problem is, when you put most 315-35-17 tires on these 10.5" wheels, you will run into two clearance issues with IRS Mustangs:


ISSUE #1 - Tires Rubbing the IRS Frame

When the car is sitting at normal ride height, the inner sidewall of the tire will rub the frame of the IRS. If it doesn't rub, it may still just barely clear it by 1/8" or less.


ISSUE #2 - Tires Rubbing the IRS Bolts

There is a suspension bolt head that sticks out into each of the rear fenderwells. These are 2 of the 4 bolts that connect the IRS assembly to the body of the car. When the rear suspension is unloaded (in other words, the car is lifted and the rear wheels are allowed to hang freely), the inner sidewalls of the tires will most likely rub against these bolt heads. This could cause serious damage to your sidewalls if it ever happened while you were driving.

IRS_Bolt_Location.jpg



To solve issue #1: You have to use wheel spacers. As long as your tires aren't really wide (believe it or not, all 315-35-17 tires are not the same width...more info below), 1/8" or 1/4" spacers will solve that problem in some cases. Other times, you'll have to move up to 3/8" spacers.

To solve issue #2: You have to remove a little bit of material off the top of the bolt heads. It's pretty easy and can be done without removing the bolts from the car.

Shaved_Bolt.jpg


boltheadgroundoff.jpg


Another option is to replace the bolts with low-profile bolts like THESE from Maximum Motorsports.




Other important tips when working with wide tires on 10.5" Cobra replica wheels:


1. If your car has been lowered, you actually gain a little extra sidewall clearance for the rear tires.

Many people who lowered their cars found that they didn't need to use wheel spacers for clearance any more.


2. All 315-35-17 tires are NOT the same width!

BF Goodrich and Goodyear 315s have a section width of 12.75" on a 10.5" wheel. A Dunlop or Sumitomo 315 only measures 12.25" on a 10.5" wheel. When you're talking about fitting wide tires on a Cobra with 10.5" wheels, 1/8" is a big deal. You can get away with using a more narrow spacer (1/8") if you stick with the Dunlop or Sumitomo 315s. If you go with the BFGs or Goodyears, you'll need at least a 1/4" spacer (and most likely a 3/8" spacer).

TIRES.gif




3. Sumitomo or Dunlop 315s (mounted on 10.5" wheels) should fit without any spacers on a stock Cobra.

The only problem you might run into is how much sidewall-to-IRS frame clearance you'll have. Sometimes it may only be 1/8" (especially on the driver's side)...and that's cutting it really close. You'll still have to address issue #2 with these tires.

Sumi315_section_width.jpg



4. As the rear springs of these cars are compressed, the action of the suspension will actually move the sidewall of the tire away from the IRS frame.

So while it may seem that you don't have much sidewall clearance (like maybe 1/4"), you will be fine.


5. If you move up to 18 x 10.5" wheels, you may not need wheel spacers at all.

18" wheels move the tire away from the IRS frame enough to keep it from rubbing in many cases.


6.The tire clearance is not exactly the same from side to side on a Cobra.

For example, many people have reported having an extra 1/8-1/4" clearance on the passenger side wheel vs. the driver's side. So when you test-fit any wheel/tire combination for clearance, always try it on BOTH sides before you draw any conclusions about fitment.


7. If you just want to run 315 Nitto drag radials on 17x10.5" wheels, you will NOT need any wheel spacers!

Nitto 315s are a very narrow tire (see the section width diagram above) and will not rub the IRS frame when mounted on 10.5" wheels. You'll still have to deal with issue #2 above to keep them from rubbing the IRS bolt heads. You can also mount any 285-40-17 on a 10.5" wheel and you won't need spacers.

285-40-17 on 10.5" Cobra Replica Wheel (no wheel spacers required):
Cobra3.jpg



8. No two Cobras seem to have the same tire clearance.

There are some people who've gotten a specific wheel/tire/spacer combination to fit on their car, while others who tried the same thing said it didn't work. So just because something works on one person's car doesn't mean that same setup will work on yours. It probably will, but it's not 100%.


9. You can solve both the wheel spacer AND IRS bolt head issue by using 1" (25mm) spacers with integrated wheel studs.

These spacers will give you enough space to easily clear the IRS frame and the IRS bolt heads without any modification. See 1" spacers HERE. Many people don't use these with 10.5" wheels because they feel that they move the rear wheel/tire out too far and gives the car an "old school" look. You can check out a Cobra with 10.5" wheels and 1" wheel spacers HERE


10. If you need a spacer thicker than 3/8", you need to install longer/stronger wheel studs.

Instructions can be found HERE


12. If you need a spacer thicker than 1/8", then get some HUBCENTRIC spacers.

Flat wheel spacers transfer too much load to the wheel studs and may eventually break the studs. Read more about this HERE. THESE spacers are very popular in the cobra community.


13. If you use wheel spacers, be sure to install them properly and check the lugnut torque several times after you drive the car around for a few short trips.

If you don't do this, you could end up breaking wheel studs and/or lose a wheel!!!


14. If you decide to use wheel spacers, understand that they definitely have the potential to be dangerous.

If not used properly, they can introduce additional stress loads which may quickly exceed the tensile strength of the wheel studs and lead to a catastrophic failure. If you don't fully understand the implications of using spacers, then don't use them.



Here are 2 other good threads (with pictures) that are worth checking out...

http://www.svtperformance.com/forums/showthread.php?t=113272
http://www.svtperformance.com/forums/showthread.php?t=195464


Simple, isn't it?!?!?!?! :-D
 
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mblgjr

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^^^^ Single greatest post ever!!!

SOMEONE SHOULD STICKY THAT POST; in regards to the question "will 315's fit?"

Put it in the tech section, something.

BTW, if it wasn't mentioned before; MM is for Maximum Motorsports. www.maximummotorsports.com
 

BadMoFo

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VintagePorscheG said:
This thread is dumb, I have button head bolts and 315 Sumitomos on my stock rims.


I was wondering if anyone had the 315 sumitomos on the stock rim. how do you like them? I am looking for a daily driver tire in a 315 size for my stock rim. I usually use the nitto dr's for their longer traed life but it seems they just keep getting shorter and shorter. wish they would make a 555 in a 315 size.
 

TrueBlueGT

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VintagePorscheG said:
This thread is dumb, I have button head bolts and 315 Sumitomos on my stock rims.

Thanks for sharing so much information. The guy's new & trying to learn. There's no reason to be a jerk to him.

Top Fuel...great post:bowdown: That should be sticky'd.

To the original poster: Just do a solid axle swap :pepper: :pepper:
 

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