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Wheel and tire size

14K views 16 replies 9 participants last post by  c_rizzle 
#1 ·
Just looking for some advice. Going to be getting some new wheels/tires for my 15 5.0. I have the base model so currently 18x8.5 wheels with 235s all around.

I'm looking at getting 19" wheels. Not sure if 8.5 or 9.5. What's the widest I can safely go with either size without staggering the wheels. I want to be able to rotate to prolong the tread life.

I guess the other pain with upsizing is calibrating for the speedometer/odometer.

Thanks so much for any insight.


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#5 ·
Your question is what is the widest wheel you can mount on the S550 without needing to go staggered? The answer is in stock form the S550 will accept 10.5 inch wide wheels on the front and rear. 11 inches are too wide on the front, but can be used on the rear.

Now before you go ordering some exotic super wheel, there are a number of other factors to consider. First is the offset. 10.5 wide with +35 offset is nice but if you put on any tire over 40 aspect ratio it might rub on the front struts. Also the wheels you select might not have the clearance over the front brake calipers, and therefore need spacers to clear. That will push them out further, and if you need more than 10mm in a spacer it's wise to replace the studs with longer ones($$). If you aren't looking to push the envelope the safe play is to go 10" wide and +40 offset(any less than +40 and you are getting close to poking out of the wheel well). 18, 19, or 20 is up to you, that width and offset though will get you the base for seriously wide tires with no rubbing issues. Doesn't matter if you are lowered or not 10" and +40 will fit.

I assume you will want square tire fitment as well. The safe maximum is 285 on the 10" wheels. It will work in the front and the rear, but as always there is a potential drawback to a tire that wide in the front. It will try to follow road grooves (pain in the butt).

To sum it all up. You want a wheel that 1st: will clear your front brake calipers (so you don't need spacers), 2nd: 10" wide and +40 offset. And for tires no more than 275 up front. (To be perfectly honest 275s might try to follow road grooves too, it's up to you)
 
#6 ·
Thank you very much road dog. That's informative and helpful. I'm thinking 19x9.5 with 275/40/19 all around. Would love staggered wheels, but I want to rotate the wheels at maintenance intervals. Hopefully no issues clearing brake calipers etc and no need for spacers with that setup. Thanks again.


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#9 ·
I'm also thinking about replacing my wheels & tires on my 2011 Mustang GT. Came with 235-55 x 18 (Coup, no premium). Looking at 19 x 8-1/2 wheels at AM (2010 Chrome GT500 only come in 8-1/2" or 10" width)) and 255-45 x 19 tires to go with the 8-1/2" width. (Little more aggressive) Any suggestion on decent tires?? Is there a noticeable difference between 45 or 40 for ride comfort ?? I'm driving that car from April 1 'till November 1. I don't want to go much larger then that, because of possible issues with speedometer, clearance, computer settings, etc. Thank you for any input.
 
#10 ·
That's appears to be a good match as far as tire diameters.
I have the 255/40R19 for my summer tires and 245/45R18 for my winter tires and didn't notice a difference as far as ride comfort.
 
#11 ·
I have 19x9.5 wheels with +35 offset and currently running 255/40ZR19 Michelin PS2's. They are a little short for my liking, but I got them at a good price. I'll be switching to 275/40ZR19's all around once these wear out. I have no clearance issues and am lowered on BMR performance springs.

Jeremy
2016 Ruby Red PP GT
 
#13 ·
new 19 x 8-1/2 wheels from AM

Hey ponie1992, thanks for your input. My only other question, AM only offer the 19" wheel that I'm looking at in 8-1/2 " or 10" width. Will the 8-1/2" width wheel works with the 255/40 ZR 19" tires ?? or should I consider the 10" width. (I don't want any clearance issues.) If you think I should go with 10" width wheels than should I consider 265/40 or 275/40 tires ??
 
#14 ·
Hey ponie1992, thanks for your input. My only other question, AM only offer the 19" wheel that I'm looking at in 8-1/2 " or 10" width. Will the 8-1/2" width wheel works with the 255/40 ZR 19" tires ?? or should I consider the 10" width. (I don't want any clearance issues.) If you think I should go with 10" width wheels than should I consider 265/40 or 275/40 tires ??
Sorry for the very late reply. Haven't been on here in awhile. I would run wider than 255 on a 10" wheel. 255 would be fine on 8.5". 275 on 10" should work fine.

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#16 · (Edited)
The Super Snake has 275/35 ZR20 Michelin Pilot Super Sports on the front (10" wide rims) and 305/30 ZR20 Michelin Pilot Super Sports on the rear (11.5" inch rim). Car is lowered 2". Deep dish lip on the front is 2". Lip on the rear is 3.25".

I will say that the 305/30 ZR20 & 11.5" rims on the rear are absolutely positively the widest possible 20" tire / rim combination for the rear. It's actually scarey to look at how close the tires are to the inner part of the quarter panel. If it weren't for how the IRS sucks in the top of the wheel ever so slightly when the suspension compresses, the tire would strike the quarter panel.

The front has a narrower distance from hub to hub than the back (back has more positive offset). Any good wheel manufacturer will put your car year/make/model into their computer and be able to calculate the necessary offset for a given wheel design for a stock GT (for each year). If you have to give the offset to the manufacturer, run away. If you are buying an off-the-shelf rim, then the retailer should be able to choose the appropriate offset for you as well...if not, find another retailer. They should all have that information in their databases. All you should need to do is give them the tire size and how much of a "deep dish" lip you want on the street side (if any at all) and they should calculate the offset for you to clear your fenders/struts/etc. 10" wide is the widest for the front and 11.5" is the widest for the rear. Due to different tire sidewall profile designs, sticking with 11" for the rears is probably the safest way to go.

On the clone I am having Avant Garde make a set of rims that will hold the same tires as the Super Snake. They know the offset and clearances. This is the closest rim I can find to match the Super Snake design. Its forged aluminum. Everything is US made. The deep dish version is a 3 piece which I wish was a monoblock....but they only make the "no lip" version in monoblock. This is a picture of the design...it is showing a no-lip monoblock rim....mine will have a deep dish lip design http://agluxurywheels.com/agl32.html

If you are going to buy rims, you need to not only get the right size, but you also need to consider cast versus forged (forged is much better but more money) and monoblock versus multi-piece (monoblock is better). Basically, a forged monoblock aluminum wheel is stronger than cast or multi-piece aluminum, holding all other things constant (please don't flame me with a steel multi-piece rim discussion as I'm not talking about drag rims here). A cast aluminum rim will be more susceptible to bending if you slam a pot hole. Multi-piece need to be inspected every now and then if you do any hard driving to make sure things are not loosening up.

Also, a 20" diameter rim will ride harder than a 19" inch due to less sidewall on the tire. 18" will be even smoother. I like the "track" look of the 20" rims and mine is not a daily driver so that's what I'm going with. If it were a daily driver I would certainly choose a 19" or 18" diameter.
 
#17 · (Edited)
Consensus seems to be: 19x9.5 wheels with +35 offset, with 275/40/19 tires

PLEASE look at wheel weights when shopping!!! I see so many people just pick some wheels based purely on appearance and price, so they end up with some 20" boat anchors (super heavy) wheels. Then they complain their car feels slower, handles worse and slams in to pot holes or, etc... Just make sure you don't go heavier or you'll be sorry.

I went from stock 245 to staggered 255 front, 285 rear and lost over 8 lbs per wheel. So it was about 34 lbs total unsprung rotational mass =HUGE DIFFERENCE. The car was faster, handled bumps better, and just felt all around better. It was immediately noticeable when I went over a set of bumpy rail road tracks that I traverse every day, and the wheels seems to just spring up & down with out "banging".

275 is about the right balance where you get "good enough" grip on the rear and don't have too much pulling / steering issues in the front.
 
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