19 vs 20 Wheels

[GN34]

I’m trying to decide whether to get the 19 x 8.5 (648) or the 20 x 9 (649) wheels.

Will there be an appreciable difference in the performance between the 19 x 8.5 (255/40) and the 20 x 9 (265/35) wheels if they were both fitted with the same tire?

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[williamwally]

Performance not really, the steering should feel marginally faster with 20's but thats probably very hard to tell. What you will experience for sure with 20's is a harsher ride and higher susceptibility to bending your rims over potholes, tracks etc.

My S4 ran on 255/35 19's. I lived in downtown chicago and tried to be good to all the wheels. Still ended up with 2 bent stockers and 4 bent aftermarket wheels :( plus having to slow to a crawl for any small thing is annoying. But if you dont live in an asphalt wasteland then you should be ok.

 

[Ericc B]

Lightness is always better in suspension components. So for pure driving pleasure a 19 inch is the better choice.

Looks wise however the 20 inch beats any 19 hands down. It's a pretty big car and 19 actually looks a tad small on it.

 

[MustangSteve]

I’m trying to decide whether to get the 19 x 8.5 (648) or the 20 x 9 (649) wheels.

Will there be an appreciable difference in the performance between the 19 x 8.5 (255/40) and the 20 x 9 (265/35) wheels if they were both fitted with the same tire?

Consider that the Mustang engineering team has opted for 19-inch wheels for the performance packs. The 20s are there for appearance purposes but for the maximum performance version of Mustang, the lighter, stiffer 19s are the top choice because unsprung mass is the enemy of both handling and ride quality.

 

[Boydstang]

I'll tell you what made up my mind, the price of tires for the 20" rims! I love the style of the 20's but I looked into tire prices for both the 19's and 20's and the 19's are so much cheaper. Now I priced them using the same tires that come on the cars, the Pirelli's, so I'm sure there are cheaper ones but seeing the price of the Pirelli's made up my mind right away without looking any further.

Go for the 19's, a little better ride as well, more rubber between the rim and the road.

Good luck with your decision.

 

[GN34]

Thanks for the information.

I was leaning towards the 19's so this helps with my decision.

I just wish the 648 wheel was 9 inches wide like the PP wheels. I understand it's an optimal width wheel for a 255 tire.

My concerns with the 649 wheels are that I only found one high performance A/S tire made in 265/35 and that there is no spare wheel/tire option.

 

[tbonez3858]

Consider that the Mustang engineering team has opted for 19-inch wheels for the performance packs. The 20s are there for appearance purposes but for the maximum performance version of Mustang, the lighter, stiffer 19s are the top choice because unsprung mass is the enemy of both handling and ride quality.

^^^This. Unless the 20s are forged and weigh less, the 19s will be much better in performance.. I saw a test of the same wheel in a 17, 18 and 19 on a test car. The car was a full second slower 0-60 and braking distance added 10 or 15 foot between the 17 and 19.

 

[5.0GT]

Smaller diam wheel will give better acceleration for the most part, the larger wheels will be better looking. I like performance over looks.

 

[Old 5 Oh]

Take your clue from Ford. Tires with sidewalls serve an important performance function. Not only are smaller rims lighter than larger ones, but there is a limit to the "lower profile is better" fad. To me, it seems like 40-series is about at that limit and coincidentally (not) that's what's on the 19-inch rims. The 35-series tires on the 20s are going to ride harshly, and as many have pointed out, they are not tall enough to protect the wheels from damage on the road.

I would LOVE to have the option of a wheel that looks just like the 20s in the 19-inch Performance Pack. I think they look perfect on DIB, and I want the PP, so I want to order something Ford isn't offering. That's REALLY disappointing to me.

The wheels are easier to change that everything that's in the PP, so my latest thought is to order the PP and start saving for replacement wheels. I've done it before, many times.

 

[Grimace427]

Take your clue from Ford. Tires with sidewalls serve an important performance function. Not only are smaller rims lighter than larger ones, but there is a limit to the "lower profile is better" fad. To me, it seems like 40-series is about at that limit and coincidentally (not) that's what's on the 19-inch rims. The 35-series tires on the 20s are going to ride harshly, and as many have pointed out, they are not tall enough to protect the wheels from damage on the road.

I agree a tire with a shorter sidewall will have a harsher ride, however the tire's aspect ratio is not referred to as 'series'. '35-series' or '40-series' is not the correct way to consider tire sidewall size as the aspect ratio is directly related to the width. For example a 255/40/19 and a 285/35/19 have a nearly identical sidewall despite the different aspect ratio.

 

[KGrGunMan]

255/40/19 = 102 mm (4'') tall sidewall.
265/35/20 = 93 mm (3.7'')tall sidewall.
305/30/20 = 92 mm (3.6'')tall sidewall.

If you want performance over anything else, don't keep any wheels ford sells on the mustang. If you want wider performance tires then 19's are slim pickings and there are a sea of 20's.

If you care about tire price over anything else then get the smallest tires you can.

If you care about comfort over anything else then don't get the PP and do get some 18's.

 

[gunman]

Thanks GN34 for posting this. I too am getting ready to order the 2015 and really prefer the looks of the 20's over the 19's but want to make sure the ride quality is OK.

Question: If I drive a 2015 mustang WITHOUT PP that has 19" and compare it to a 20". Will I notice the ride quality on day to day driving? I get the whole performance thing, but the power and performance w/o PP is already going to be amazing for me.

 

[aspensilver]

gunman - yes, still noticeable. 20" will be slower and worse ride quality

 

[KGrGunMan]

Standard GT wheels: 235/50/18 = 4.6'' sidewalls.
GT PP front/non-PP optional 19's: 255/40/19 = 4'' sidewalls.
Optional 20's: 265/35/20 = 3.7'' sidewalls.

Many other things can affect comfort too, like what different tires we're used? Performance tires tend to have a stiffer sidewall, so a high mileage tire with smaller, but softer sidewall could ride better than a bigger sidewall that is very stiff to decrease flex. On top of that you can throw in a run flat tire that is extremely stiff and kill your ride even with the 18's.

I couldn't find what specific tires we're going to be used for anything other than the GT-PP, if someone could clue me into that info i'd love it.

I tried to stay consistent with regards to weight and picked a single tire for all sizes (Pilot Super Sport)
235/50/18's are 26lbs.
255/40/19's are 26lbs.
265/35/20's are 26lbs.

So the tires are not heavier, it's all down to the wheels and how much they spent to make them. On the market one can find 21lb 20's and 30lbs 18's, but typically more weighs more. I'd think the 2lb per wheel gain and 1/4in of sidewall loss will not be noticed as much as what specific tire is on the wheel.

 

[Sig556]

There seems to be some controversy over the ride and comfort of the 20" wheels and tires. Have you noticed most of the advertised vehicles on display all over the world have been wearing the 20 inch wheels and tires? I'm not sure but I'm willing to bet Ford has dialed in the suspension on these packages and a comfortable ride will be one of these things.

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