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Discussion Starter #1
Hey guys! I need to get some new rims and tires for my 2014 GT. I have the basic stock 18x8 rims with 235/50/18. I would like to get a bit wider tire all around, was thinking 245 or 255. I was told I need to run a wider rim like 18x9 to upgrade to a wider tire or just upgrade to 19s. Not sure what to do here. What are the pros and cons of getting a bigger rim. Will having a taller rim make me lose speed? Is there any good recommended rim size? Not sure what to do here. Any suggestions? What are y'all running? Also, what are some good websites to purchase rims besides American Muscle?
Thanks in advance
-Nick
 

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Yes, in theory you lose some speed with bigger/wider wheels and tires (because they're heavier). In reality, no, you don't. Mostly because the 235's aren't enough for our cars. Going to a 285 in the rear really improved my 0-60, 1/4 mile, however you want to measure it. Instantly noticeable. Maybe I lost some triple digit roll on speed, but how often are doing roll on racing at that speed?

Bigger isn't always heavier though. SVE makes some wheels that aren't any heavier than your stockers, and LMR's package deal has 305's in the rear (or you can get a 285 square set up).

The SVE R350's are super light (my buddy has them and we weighed them with tires mounted, and they aren't any heavier than stockers with 235's). But don't get caught up on weight. In the real world daily driving, it's not anything to worry about. I have heavy 20's, and my car isn't slow and my buddy with his light weight 19's is barely faster in a drag race, and I mean barely. Maybe wins by a bumper, but he does win, every time.

https://lmr.com/products/10-14-Mustang-Wheels
 

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These cars are fairly heavy and basically the more rubber in contact with the road, the better. And 245 is about the widest you should put on the original 8" wide wheels; so you do need both wheels and tires if you want to go substantially wider than original.

A wider tire does have more rolling resistance so there could be a small loss of gas mileage, if that matters.

If you buy lightweight wheels, then the weight penalty for larger diameter wheels is very small, or could be a weight savings, like Old Goat already said.

To maintain your original overall gearing, keep the speedometer accurate, and have no change in acceleration (due to gearing) you want the same overall diameter tires as the original. for most Mustangs this is about 27.2"; you can check your exact original tires to find the tire diameter. Usually when people go from 18" to 19" wheel, the tire outer diameter stays the same, because they select a tire with lower sidewall to make the outer diameter the same as it was before.

Tire Rack is a great place to shop for wheels and tires. They have a tool that shows what the wheels will look like on your car. Their tool might be a little sticky about staying with the original wheel diameter; but I think you can force it to let you change the wheel diameter. They also have full tire specifications, including the overall diameter and the recommended wheel width.
 

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A wider tire does have more rolling resistance so there could be a small loss of gas mileage, if that matters.
Ack, yes, this is a good point. My MPG with my heavy 20's went down from roughly 19.7 to 18.4, overall. Same commute, same city/freeway split. I don't know how MPG is calculated though. My new tire size in the rear is a little more than 1/2" taller than stock overall. I don't know if all my MPG loss is from added weight/rolling resistance, or partially from wrong calculation from slightly taller tire, which slightly changes overall gearing. I'm not mathematically smart enough to do the math for that haha. Well, I am, I'm pretty good at math, but I don't know what equation is needed to know.
 

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Discussion Starter #5
Thanks for the info guys. So if I wanted to go 19s and stay the same wheel/tire diameter to keep from messing with the speedo, I could do something like 255/45/19 or 245/45/19? from 235/50/18. Or would I have to go to a lower side wall of 40?
Thanks.
 

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here's how you can figure all that out:

1) go to tirerack.com
2) look up your old tires -- several ways you can do that; but in the end you want your old tire make/model/size on the screen
3) go to the "specs" tab and take note of the "overall diam" -- this is the overall diameter that you want in your new tires (within about 0.2 - 0.5")
4) scroll down in the "specs" list and look for the new tire sizes you are considering (you might need to select a different make/model to find the size that you want)
5) compare the "overall diam" to the diameter of your original tires . . , then:
- if the new size is smaller, look for another size with higher width or the aspect ratio
- if the new size is taller, look for another size with lower width or aspect ratio

when you find a size that looks good; also check the "rim width range" to see what size wheels should go with those tires

the wheel wells can easily accommodate up to about 285 width, as long as the wheel offset is correct (actually you can go even wider but I got the impression that you don't want to go super wide, plus you need to be more careful about wheel specs with the wider widths)
 

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. . . My new tire size in the rear is a little more than 1/2" taller than stock overall. . . . .
. . . and I assume you did not correct the odometer. So you are traveling a little farther on each rotation of the tire than the odometer thinks you are; so you are actually traveling more miles than the odometer says; so your real MPG is a little better than what the odometer and computer calculate. But it is a very small difference . . . about 3%, which would only account for about 0.6 MPG
 

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. . . and I assume you did not correct the odometer. So you are traveling a little farther on each rotation of the tire than the odometer thinks you are; so you are actually traveling more miles than the odometer says; so your real MPG is a little better than what the odometer and computer calculate. But it is a very small difference . . . about 3%, which would only account for about 0.6 MPG
Yeah, I didn't correct speedo for the small amount, and your math sounds right.
 

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Discussion Starter #9
Thanks JBert for all the help! That made it super easy. Much appreciated. Also, one more quick question guys. I live in Arizona and I have always had all-season tires on my Mustang, but I've been wondering about summer/hi-performance tires. Obviously they aren't going to be as comfortable or quiet. Would they make a daily driver tire? How well do they hold up compared to all-season? What tires do you guys have?
Thanks!
 

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. . I've been wondering about summer/hi-performance tires. . . . Would they make a daily driver tire? How well do they hold up compared to all-season? What tires do you guys have?
Thanks!
you're welcome . . . summer/high performance tires are fine for a daily driver, but they do tend to wear more quickly than less sticky tires. Most are 200-300 treadwear rating which means something like 10,000-30,000 miles depending on which tires and how you drive. Basically the softer they are, the stickier they are, and the quicker they wear out. I have Michelin Pilot Super Sport which is a fairly expensive summer tire, because I plan to get back on the road track someday; they work fine for me on the street but I don't expect them to last very long. I don't put many miles on my Mustang any more so it's not a big deal to me, but that could be an issue if you drive a lot of miles. Tire rack is a good resource for reviews and ratings also.
 

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Thanks JBert for all the help! That made it super easy. Much appreciated. Also, one more quick question guys. I live in Arizona and I have always had all-season tires on my Mustang, but I've been wondering about summer/hi-performance tires. Obviously they aren't going to be as comfortable or quiet. Would they make a daily driver tire? How well do they hold up compared to all-season? What tires do you guys have?
Thanks!
I'm in California and I run summer tires all year (Nitto 555 G2) with no problems. They aren't uncomfortable, and they aren't really loud either. They do just fine in the rain too. On the rare days it's really cold (high 20's, low 30's), traction is crap, but as long as you don't floor it, they're fine. No issues with them last winder.
 
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Continental makes an outstanding all season in my opinion - I had a set of DWS on my old 2012. If you don't need cold weather tires then definitely go summer ho Perf - I installed a set of BFG Sport Comp2's this past spring and they are great - easily the match of my old Mich SuperSports at half the price. Sticky and predictable in the dry, great in the wet and with about 10k miles on them now almost no appreciable wear - even on the rears 😎
Good luck picking rims - I fall in love with a different rim about once a week......I will say that a 2014 GT needs at least 19 X 9 - luckily there's only about a million to choose from......heh

Scott
 
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