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Tire recommendation/widest tire?

2007 - 2014 
33K views 70 replies 15 participants last post by  Goose17 
#1 ·
Something I've been thinking even before I bought the car was what tires to go with on the rear to replace the original Goodyear F1's. The prior owner told me it would probably need a set fairly soon as they just don't perform that well. In doing so, I've also thought about trying to put the widest tire I could on a SVTPP 20" wheel that would still keep my original height for speedometer purposes.

The tire that I've been thinking about is the Firestone Firehawk 500. It seems to get really good reviews and is one of the cheaper ones. Seems to be a best bang for the buck.

Has anyone tried to put a wider tire on the 20" Performance Pack wheel? If so what did you use? How did it work out?

Thanks.
 
#2 ·
Depends on your current/future power mods and if you drive the car in the rain. If you have big power and drive the car only on dry days, a drag radial might be best suited for you. I have Toyo R888's which are darn near drag radials with super soft compound and some serious traction. I squeezed a 295 onto a 9.5" wheel without any issues at all. I have 19" wheels in the back of my car.

You can always have your wheels widened, but I didn't want to go that route.
 
#3 ·
Thanks for the reply Goose. I prefer to keep things original or at least be able to return to original so no widening of wheels. Things like originality of tires aren't a concern though. I don't plan to drive it in the rain but you never know. I have thought about using some sort of Drag Radial but the dollar per treadwear is not a very good deal. So the 295 was the answer I was looking for. Did it throw off your speedometer much?
 
#4 ·
The width will not affect your speedometer. The height will. Since the height of my tires (sidewall) wasn't much different than my original tires, I didn't see any noticeable change.

Not all 295's are the same width. For some reason, some manufacturers run on the wider side and others are on the skinnier side. My Toyo R888's recommend a 10" wheel as a minimum, but other than a little sidewall bulging/pinching, there is ZERO side effects from the wider tire. The car is stable, planted and accellerates wonderfully.

Hope this helps. Thanks for using the wheel/tire section by-the-way. It's much more visible/locatable now that I moved it.
 
#5 ·
Thanks for the info. Yes sir, I looked at a conversion chart and there isn't much difference. I just knew that 35% of 295 would be a little taller than 35% of 285 but just didn't know by how much.

No problem on using the right section. I try to do what I can to make it easiest for the forum, especially the mods. :)
 
#6 ·
I've just installed a set of the Firestone Indy 500's. Don't have a full review yet, but they seem on par traction wise as Continental Extreme Contact DW. (which is better than Goodyear F1's)
 
#10 ·
I am running Michelin PSS 295s on my rear and they are great. I could probably find something with a little more dry traction but I daily drive my GT500 so I need wet traction too. The tread wear on the PSS is also great, they are rated for 30k and I believe it based on the wear I have seen so far. (around 6k on them now and they were used when I got the car), even with some spirited driving.

Sent from my VS990 using Tapatalk
 
#11 ·
I am running Michelin PSS 295s on my rear and they are great. I could probably find something with a little more dry traction but I daily drive my GT500 so I need wet traction too. The tread wear on the PSS is also great, they are rated for 30k and I believe it based on the wear I have seen so far. (around 6k on them now and they were used when I got the car), even with some spirited driving.
Thanks. They seem to be a really popular tire. Factory issue on some Porches I kept seeing.
 
#13 ·
Well, I ordered 2 Continental ContiSportContact 5P in 295/35/20 for the rear. We'll see how they do because they are used with about 55% tread left. I noticed on Saturday I've probably got about 10% left on my tires now that are original to the car. Hopefully, I can use these for awhile.
 
#16 ·
My Continental's came in today. I must say I'm pleasantly surprised with the shape they're in. They advertised about 55% tread left but it looks like they have more. Anyway, we'll see what the shop says when I have them put on Saturday morning.

At least I have 2 tires on there now that I can abuse since I have 2 spares! :grin:
 
#17 ·
I had the tires mounted and balanced this morning. My friend and the owner at the shop both said they were in great shape. I had an old tire pressure sensor in the right rear. They took it out of course.

The 295's fit just fine. They look right at home on the stock 20 in. wheel.

First impressions are really good. A lot more traction. The car feels more controlled and not so squirrelly.
 
#18 ·
I wanted to fit the maximum size in the rear for road racing and heard I could get 315/35ZR20s if I had the rims widened. I had the stock 9.5" rims widened to 11.0" at Weld Craft in Livonia, MI. They did a perfect job at $ 300 each. The extra width was added to the inside. I got Nitto 555 G2s installed, but not before I got BMR lower control arms (TCA-022, $209./pr) and the BMR PHR013 pnahard rod ($139.) so that the rear axle doesn't move up or down (no wheel hop under extreme acceleration) nor any side-to-side movement. These axle components are absolutely necessary with that size tire because you cannot slide a finger between the inner tire wall and the fender well! The factory suspension pieces are stamped steel with rubber bushings. The BMR models I got are much thicker moly tubing with polyurethane busings on one end and a spherical bearing on the other. Not much of a ride sacrifice (I should care on a car like this?) and the tire is very happy in it's new home. I even had the US driver take a cameraphone picture, laying on the ground. The difference between the Nittos and the OEM Goodyears? Unbelievable! I don't know whether it's just the size or the tire design but the Nittos hook up waaaaay better. I love this setup. Now for the fronts. Maybe just going to 275/40ZR19 with no rim change.
 

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#20 ·
Nicely done and Welcome!

I plan on changing the rear suspension pieces out sometime after this fall when Maximum Motorsports has their fall sale (if finances allow). But I would want to keep my stock SVTPP wheels too. However, just didn't want to do something that couldn't be reversed.
 
#19 ·
#21 ·
I wanted to keep everything looking stock plus, when I shopped for 20" X 11" rims, they turned out to be more expensive and I would have had to buy four to have them all match. A no brainer for widening just the rears. In this mod, I don't see any reason for reverting back to stock. The downside to putting this much tire in that fenderwell: No "wiggle" room at all. It took me close to an hour to put the first one on, but by sliding shim stock on the ground under the tire, the second one went on in 15 minutes. The wheel has to go up into the fenderwell perfectly straight both up and down as well as side to side a line up with the bolts perfectly. Just remember, going this route makes those suspension component changes a must. But you get a much better driving car for it with unbelievable tracking and absolutely no wheel hop. With only 20 rwhp difference and the 500# lighter GT500, no stock Hellcat can touch it let alone on the road course track. See me smiling?
 
#26 ·
Sooooo, if I want to go with widened stock 14 rims, my choices are:

10.5" width and no spacer or
11" and a 1/2" spacer?

I was hoping to widen to 11" and run a 295/35 or 305/35 and a 1/4" spacer to avoid the longer studs.

Catmonkey, what are you thoughts?

Anyone else that has definitive knowledge for this?

Tom
 
#27 ·
I would say, rim width selection should probably be based on the narrowest recommend size for the tire you selected. You can get by with the 10.5" width with up to a 315. Any bigger and you would need to go up to the 11" width. As far as tire width recommendations, you would have better cornering properties leaving toward the wider end of the spectrum of the manufacturer's recommendation, but you have less clearance issues with the narrower range. There is adequate stud thread contact with a 1/4" spacer. Swapping out to longer studs is not a difficult modification either. As far as 315/35-20, I've come to the conclusion that it's an awfully tall tire for the wheel well. I swapped 325/30-20s on my 11" rims and the cross section was not wider than the 315/35-20s, so that's another consideration. It's the same tire diameter as the 285/35-20. I think anything bigger than a 305 you should remove the bump stop brackets.
 
#33 ·
I am running SS rims on the rear that are 20x11. Tires are Nitto Invo 315/35s I have zero rubb with Ford Racing L Springs and a Panhard Bar. I want to be able to swap from these rims to the OEM rims just to change things up every few months. And, I just have a soft spot for OEM rims. That is the reason for my question. I know what I have fits, but I am concerned about the spacer needed if I go with widening OEM rear rims to 11". I don't want do deal with studs because I believe they will be a problem when running the SS rims, which don't need a spacer. I also agree with 315/35s are taller than I would like.

Here is a picture of the current setup.
 

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#28 · (Edited)
I looked up on a tire size calculator and the 335/30-20 is the same diameter as the 285/35-20. Both are 27.9" in diameter. The 325/30-20 is very close at 27.7" in diameter. IMHO, I think 335 is too wide. Not saying it won't look good, just probably not worth the hassle.

With that being said I put on 295/35-20 with are in effect .7% taller than the 285 while the 325/30 is .7% shorter. Making a negligible difference.
 
#29 ·
While the stated uninflated diameter is different, the rev per mile data is the same for the 285/35-20 and the 325/30-20 would have the same loaded radius. A 335 needs an 11.5" rim. Everyone I've seen pics of are sticking out the rear wheel well. I shoot for as close to flush with the rear outer lip as close as I can get it.

I just bought a set of second hand set of True Forged wheels with tires. Tires have less than 500 miles on them. I'll have a set of 295/35-20s in MPSS for sale shortly if anyone is interested.
 
#31 ·
The 315/35ZR20 Nitto 555 G2s that I have on the rears now have the overall diameter of 28.66" and a cross section width of 12.6". Nitto don't go bigger than a 315. The other tire I was thinking of was the Michelin Pilot Super Sport and in the same size their OD is 27.2" and an a width of 12.3" so the Michelins are smaller in both direcitons. If I thought I could get a 325/30R20 Michelin in the wheel well, they say that size has an OD of 28.7" and a width of 12.6" so I wouldn't be picking up anything I don't already have but paying a lot more money for them. All these specs are with the tire inflated. Also, I misspoke on the spacer. It's only 1/4" so I'm hoping the stud length will stand up to the road racing loads. The tire just barely "peaks" outside the the OEM mudflap.

The OEM tire, Goodyear F1 G2 size 285/35ZR20, has a cross section width of 11.4" and an OD of 27.9". So the new Nittos solve a couple of problems: A) 1st, 2nd and 3rd geAR "hookup" are much, much better than with the OEM tire and B) the wear is also much better with the Nittos tire design over the OEM. There is a difference in revs/mile with the larger Nitto at 725 vs. 750 for the OEM. Interestingly at 726 for the same size Michelin. I am not a "drifter." Got lotz of other places for my money than constantly replacing expensive tires.
 
#32 ·
Rev per mile data is available on most manufacturer's websites and TireRack also has that information for most tires. From there divide 63,360 (inches in a mile) by the rev per mile data. Take that result and divide by pi, and than half it for loaded radius. The rev per mile data is tire revolutions per mile and is what the factory PCM uses as an input for the speedometer/odometer calculations.
 
#34 · (Edited)
Putting a smaller tire on a similar sized rim and the sidewalls could be just as wide. Here's a photo I took of a 295/35-20 MPSS and 325/30-20 MPSC2 both mounted on 11" rims. The cross section is virtually the same. There would be less clearance issues with the 295 because the tread width is narrower, but from a rubbing standpoint, it's no narrower within the wheel well. I'd do 10.5", which should put the wheel/tire in what I consider to be the best offset for wider rubber for adequate clearance both inner and outer.

 
#35 ·
The 10.5" rim width is what I'd do too, next time, using the 315/35R20s. I wanted to retain the OEM wheel look and that's why I had the OEM rims widened by WeldCraft.....and I didn't have to buy four rims to have them all match! Down the road I may switch the rear gear to the 3.73:1 if I decided I need more scoot off the line, but I'm pretty damn happy with the way things are at the moment.
 
#36 ·
I didn't inspect the bump stop bracket and maybe I should though taking the much larger tire/rim off and on is a real pain because of the lack of "jiggle" room in the well. The spacer is a little over 6mm so I'm hoping the loss of stud length is minimal....at least less than a 8mm spacer. So far, so good.
 
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