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2012 SVTPP with a heavy dose of 2013 components
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My goal was to put 285/35-20s on the front and 315/35-20s on the rear. The tires under consideration are to be Michelin Super Sports. Since the 315 calls for a minimum 10.5" wheel width, I acquired 2 SVTPP 20" wheels and sent them to Eric Vaughn to be widened to 11".

The problem with my decision is that the 315/35 is 28.7" tall. I figured I was going into uncharted territory by going this route Unfortunately, Michelin doesn't make a tire that wide in a 30 aspect ratio. It would have only been .25" shorter than the 285/35. My car is lowered in the rear about .8". I knew I would have to cut out the rear bump stop bracket that is spot welded to the frame with the amount offset the widened stockers were going to give me. I had also acquired a set of Zombeast's bump stop location brackets to move the bump stop inboard, since that's needed once the bracket is removed.

I planned to simply move my rear wheels and tires to the front. The weekend I was planning all this, I got wind in a thread that another member has done it, but there is insufficient clearance with the Brembo caliper. He had to use spacers and ended up with longer wheel studs for even wider spacers. I set out to figure out if the Ford Racing 19x10 SVTPP knockoff might be a better choice since they state it will fit with the Brembo's. I took measurements with the stock wheel and determined with the offset, I'd probably be better off sticking with the 19x9.5 stockers and going with a 285/40-19 tire on them. It's 28" tall, so there would be less rake with these anyway.

Now for a little real world math. While the tire's circumference is 28.7" (315/35-20) vs. 27.8" (285/35-20), just how much taller is this tire in terms of actual change in gearing. I got the rev per mile data off each tire and computed the loaded radius. That measurement is going to determine how much taller that tire is from the ground. The circumference is the measurement at the middle and tallest part of the tire. The stock 265/40-19 came in at 13.16" while the 285/40-19 came in at 13.57". That means the car is going to sit about .41" higher in the front. Based on my measurements, it will clear the strut and tuck the tire in far enough to stay away from the front fender. That was a go, tires ordered. Because the stud on the sway bar link sticks out a good bit into the wheel well at the mounting point on the strut, I added a couple washers in between the stud and the strut.

It turns out the measurement on the rear isn't as extreme as you might think. The 285/35-20 loaded radius was 13.55" and the 315/35-20 measurement was 13.83". Hmmm.... that's only .39" taller in the rear. That's only a 3% change in the effective gear ratio. First gear is so short anyway, this might not be a bad thing. But this sucker is 12.6" wide vs. the 11.4" for the stocker and it's all going inboard. No question, the bump stop bracket will not be able to remain in place. I confirmed this with a test fit once the tires were mounted. It clears with a load on the axle, but lift the body from the axle and it's big time rub city.

When I set out to do this, I had read another members thread about his fitment of some 305/35-20 Nittos on his car with the same widened wheels. He indicated he needed to remove the plastic inner fender liner because he was getting some rubbing. The liner is held in with 6 studs mounted to the wheel well with some plastic nuts. They came out easy enough. I didn't like the studs on the top hanging precariously down, so I ended up cutting them off.

This member also cut off his bump stop bracket with a grinder. I decided to use a spot weld cutter as I had seen on Justin Starkey's thread in his VMP forum. The spot welds on the bracket are somewhat of a challenge. There are four spot welds at the top of the bracket and 5 spot welds on the bottom of the bracket. I used a 3/8" Blair spot weld cutter and bought a bunch of double sided bits. Short of removing the rear axle, you will not be able to drill the bottom spot welds unless you have a right angle drill. This wasn't nearly as difficult of a task as I thought it would be, but it's not for the faint of heart. I only used two of the double sided spot weld cutter bits for the whole car. So I ended up with quite a few bits left. After about 4 spot welds, they don't cut quite as easily as a fresh bit.

Since the bump stop no longer lines up with anything once the bracket is removed, you have to move it inboard so it can impact the subframe of the car. Otherwise, you have no bump stop in place. Zombeast makes a relocation bracket that is a simple bolt in. I think he's selling these on ebay now.

So what are the results? The front tires clear and I have not heard any evidence of rubbing. I had them on a week before I got around to doing the rear clearance work. The back is showing some evidence of rubbing on the inside of the wheel well on an off camber steep driveway. Since there is plenty clearance between the wheel and the fender, I ordered a pair of 1/8" spacers to see if that will give me enough clearance. I'm pretty sure there is enough room for .25" spacers, but I'm going to wait and see what happens with the other first.

I did take pictures along the way and will post them up next week. I'll get some shots of the car too. If you're in Beeville this weekend, look me up and check it out first hand.
 

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Okay, this will be more a teaser since I won't be able to post any pics up until next week. My goal was to put 285/35-20s on the front and 315/35-20s on the rear. Tires being Michelin Super Sports. I acquired 2 SVTPP 20" wheels and sent them to Eric Vaughn to be widened to 11".

The problem with my decision is that the 315/35 is 28.7" tall. I figured I was going into uncharted territory by going this route Unfortunately, Michelin doesn't make a tire that wide in a 30 aspect ratio. It would have only been .25" shorter than the 285/30. My car is lowered in the rear about .8". I knew I would have to cut out the rear bump stop bracket that is spot welded to the frame and I had a set of Zombeast's bump stop location brackets to move the bump stop inboard.

I planned to simply move my rear wheels and tires to the front. The weekend I was planning all this I got wind in a thread that another member has done it, but there is insufficient clearance with the Brembo caliper. He had to use spacers and ended up with longer wheel studs for even wider spacers. I set out to figure out if the Ford Racing 19x10 SVTPP knockoff might be a better choice since they state it will fit with the Brembo's. I took measurements with the stock wheel and determined with the offset, I'd probably be better off sticking with the 19x9.5 stockers and going with a 285/40-19 tire on them. It's 28" tall, so there would be less rake with these anyway.

Now for a little real world math. While the tire's circumference is 28.7" vs. 27.8" just how much taller is this tire. I got the rev per mile data off each tire and computed the loaded radius. That measurement is going to determine how much taller that tire is from the ground. The circumference is the measurement at the middle and tallest part of the tire. The stock 265/40-19 came in at 13.16" while the 285/40-19 came in at 13.57". That means the car is going to sit about .41" higher in the front. Based on my measurements, it will clear the strut and tuck the tire in far enough to stay away from the front fender. That was a go, tires ordered.

So the measurement on the rear wasn't as extreme as you might think. The 285/35-20 loaded radius was 13.55" and the 315/35-20 measurement was 13.83". Hmmm.... that's only .39" taller in the rear. That's only a 3% change in the effective gear ratio. First gear is so short anyway, this might not be a bad thing. But this sucker is 12.6" wide vs. the 11.4" for the stocker and it's all going inboard. No question, the bump stop bracket will not be able to remain in place. I confirmed this with a test fit once the tires were mounted. It clears with a load on the axle, but lift the body from the axle and it's big time rub city.

When I set out to do this, I had read another members thread about his fitment of some 305/35-20 Nittos on his car with the same widened wheels. He indicated he needed to remove the plastic inner fender liner because he was getting some rubbing. The liner is held in with 6 studs mounted to the wheel well with some plastic nuts. They came out easy enough. I didn't like the studs on the top hanging precariously down, so I ended up cutting them off.

This member also cut off his bumpstop bracket with a grinder. I decided to use a spot weld cutter as I had seen on Justin Starkey's thread in his VMP forum. The spot welds on the bracket are somewhat of a challenge. There are four spot welds at the top of the bracket and 5 spot welds on the bottom of the bracket. I used a 3/8" Blair spot weld cutter and bought a bunch of double sided bits. Short of removing the rear axle, you will not be able to drill the bottom spot welds unless you have a right angle drill. This wasn't nearly as difficult of a task as I thought it would be, but it's not for the faint of heart. I only used two of the double sided spot weld cutter bits for the whole car. So I ended up with quite a few bits left. After about 4 spot welds, they don't cut quite as easily as a fresh bit.

Since the bump stop no longer lines up with anything once the bracket is removed, you have to move it inboard so it can impact the subframe of the car. Otherwise, you have no bump stop in place. Zombeast makes a relocation bracket that is a simple bolt in. I think he's selling these on ebay now.

So what are the results? The front tires clear and I have not heard any evidence of rubbing. I had them on a week before I got around to doing the rear clearance work. The back is showing some evidence of rubbing on the inside of the wheel well on an off camber steep driveway. Since there is plenty clearance between the wheel and the fender, I ordered a pair of 1/8" spacers to see if that will give me enough clearance. I'm pretty sure there is enough room for .25" spacers, but I'm going to wait and see what happens with the other first.

I did take pictures along the way and will post them up next week. I'll get some shots of the car too. If you're in Beeville this weekend, look me up and check it out first hand.
You will Love the 315-35 20 michelin 's I have them on a hot day with 699.5rwhp and 677lb tq. they will hook up at the top of 2nd gear with the other 2 sets of tires it would only hook at the top of 3rd gear with 373 rear end gears .Also they handle great 428cj
 

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Darn, I thought this was a thread on big meat like a roast or lamb chop etc. or possibly a thread on turkey with Thanksgiving coming up!!
 

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2012 SVTPP with a heavy dose of 2013 components
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Discussion Starter #5 (Edited)
I'm a bit past due in getting these pics up, so here goes. As indicated in my objective, this is a comparison of the 315/35-20 and the stock 285/35-20.





Here's a couple shots of the widened rim. I didn't think to get a shot before I had the wheels powder coated and the tires mounted. You'll notice the indented portion of the wheel is where they cut the OEM rim and welded on the new section to make it 1/5" wider. Nice bead work on the added wheel section.





Here is the wheel well before I got started. The liner is more of a fiberglass type lining that is held in place with plastic nuts on studs inside the wheel well. It's just a matter of unscrewing the nuts and removing the two push pins and then man handling it out of there.





Here's the liner piece that was removed.



Notice the studs dangling precariously down. I removed the two studs on top and will probably cut the remainder out.



The wheel well without the liner. The bracket with the 4 spot welds showing is what I'm removing. The 4 spot welds on the top are not difficult, but the 5 on the bottom are a bit of a challenge and will necessitate a right angle drill unless you want to drop the axle.



Here is a close up of the bracket and the welds. Lots of material welded into the holes.



Since I can't drill out spot welds and hold a camera, we'll have to fast forward to the pics of the removed bracket. The scratches in the paint are from using a small crowbar to pop the bracket loose.



You can see the small indentions in the center of the built up material that remains from the spot weld. The instructions for the cutters indicate to use a punch to indent the metal. Since the weld material is not that soft, those indentions didn't keep the cutter from walking. I used a very small drill bit to make them a little deeper and it held the cutter in place. The cutter has an internal set screw so you can set how deep the cutter is allowed to go. While it may not seem like it, the cut material around the weld is flush with the surrounding sheet metal.



Now a little protection for the bare metal and cover the scratches with a little gloss black spray paint. Note the dust cover has been removed from the shock. I'm not sure it had to go, but I suspect it did. It's a very easy job on a Koni Sport.



Here is Zombeast's relocation bracket for the bump stop bolted into place. If you notice the forward screw on the relocation bracket, that is where the bump stop was originally mounted. Without relocating the bump stop, it has no bracket to contact when the axle is under hard compression.



Here's the finished product. Notice how much better the rotors look from the first shot. They are Full Tilt Boogie Racing's two piece rotors.

 

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Discussion Starter #6
Here's a shot from below with the tire mounted. It's tight with this much offset. I have a 1/8" spacer on there now, but will be going to a 1/4" spacer. However, it's going to take the installation of longer wheel studs. I'll update this thread for that project. That dust cover would have been awful close to the tire.

 

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Good job Catmonkey, looks like you made it work. I dont have the specs in front of me Toyo vs Michelin, BUT something to keep in mind for those who want to go 315 rear. When running a wider tire, the tire is what causes rubbing problems not the rim. The wider the rim, the flatter the sidewall. Narrower rim, bulged sidewall. The offset on stock wheels vs Alcoa also comes into play. But on my car i went 11.75" 315 rear & had no trouble with the bumpstop brackets. Not trying to jack your thread, just making people aware. The common fear on widening is thinking its the wheel causing problems when its usually the tire sidewall. Its hard to picture, but you can run a 315 on a WIDER wheel & end up with more room under the car. Just saying.
 

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285's on the front....I don't understand why people do this...makes ZERO Sense....but to each his own.....
 

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That Width for a front tire......what is the purpose of that size for the front? Seems like half the guys here only drive their Shelbys on the weekend as it is....haha
 

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Discussion Starter #11
285's on the front....I don't understand why people do this...makes ZERO Sense....but to each his own.....
My logic was to put a taller tire on the front to compensate for the increase in the rear, which is similar to the way it was equipped from Ford. I don't think it's a bad idea to go wider in front when you going wider in the rear.
 

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Discussion Starter #12
The offset on stock wheels vs Alcoa also comes into play. But on my car i went 11.75" 315 rear & had no trouble with the bumpstop brackets. Not trying to jack your thread, just making people aware. The common fear on widening is thinking its the wheel causing problems when its usually the tire sidewall. Its hard to picture, but you can run a 315 on a WIDER wheel & end up with more room under the car. Just saying.
It really is all about the offset. I figure your offset by widening to 11.75 is putting you at about a 53mm positive offset. My offset is 69mm widened to 11", so my wheel centerline is 5/8" further under the fender than yours. Had you widened your wheel to 11", you'd be at a 44mm offset, so it would move more of the tire outside the well. At 44mm, it would be an 1" further outboard than mine.

Widening the OEM wheel more would further exacerbate that problem for me by moving the wheel further inboard. Moving the wheel inboard puts things closer to the bumpstop bracket. The wheel won't impact the bracket, but the sidewall will hit when the axle moves away from the vehicle. The outermost portion of the cross section is a good 3/8" past the outermost portion of the rim. You may never encounter a problem while driving, but it was not a chance I wanted to take and still wanted the tire tucked under the fender.

I'm not saying one method is better than the other, but simply trying to explain the dynamics of offsets and it's impact on widened wheels. The Alcoas are a fine looking wheel, but I like the stealthier look of the stock wheels. I'll get some shots of the car this weekend and post those up.
 

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I agree with the differences in our setups. Stock wheels vs Alcoa's. For those going either way, these two examples are pretty much what it takes to make it work. I'm no expert but I am a research junkie. I bugged Robert M many times before I started cutting up wheels. I've answered many pm's since & passed along the info, so get ready. Good job. Looking forward to the car pics.
 

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285's on the front....I don't understand why people do this...makes ZERO Sense....but to each his own.....
+1

I agree with you, I've never understood using spacers either...Why put more unsprung weight on the corners?

Spacers = Your wheels don't fit.

JMO
 

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Discussion Starter #15 (Edited)
Here are a few pics I had on my phone. Not good quality, but it does give you an idea of the placement of the tires in the wheel wells.







 

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Discussion Starter #16 (Edited)
+1

I agree with you, I've never understood using spacers either...Why put more unsprung weight on the corners?

Spacers = Your wheels don't fit.

JMO
No spacers on the front. As far as unsprung weight I have a set of Full Tilt Boogie Racing rotors on the front that more than displaces the weight of the tires.

And a little wheel spacer tech from Maximum Motorsports. Sure I could spend $4,000 on a forged set of wheels with the optimum offset, but I didn't have to. A 1/4" aluminum spacer weighs 2 oz. Oh yeah, I've displaced a pound and half with the FTBR rotors per axle in the rear too.

Maximum Motorsports spacers



Tough crowd.
 

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That Width for a front tire......what is the purpose of that size for the front? Seems like half the guys here only drive their Shelbys on the weekend as it is....haha
My 285/40x19 MPSS's that I put on my '13 SVTPP fronts gave my front splitter 6" ground clearance instead of ONLY 5" with the OE DY's! Probably 90% less splitter scrapping! I have noticed no diff in handling, but I haven't been on a track.

I have not analyzed why I got a full 1" of splitter ground clearance increase, since spec wise is should have been only 0.3", but I am happy!
 

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Discussion Starter #18
If you reduced the rake in the rear, that would account for more clearance at the splitter. I installed that splitter on my car to run the Texas Mile. It scraped just as much with the new rubber as the OEM. It's now off the car.
 

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Congrats on finally getting this done. Looks great and definitely sets your car apart from most Shelbys you see at cruises and shows.
 

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Discussion Starter #20
Thanks, this was my first purchased mod. Little did I know you'd still be making these a year and half later. Hope you recovered from Sandy.

I didn't mention this, but those pics are before the current 1/8" spacer in the rear.
 
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