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Discussion Starter · #1 ·
Hello everyone, this is my first build and I’ve gotten pretty excited with everything I’ve done under the hood. Now I’m moving onto exterior.

I am currently replacing the stock premium wheels which I believe are 19x8.5, with new 19x9.5 wheels all around. Anyone know a good tire size to go with and if I am going to have to do any additional work?
 

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Hello everyone, this is my first build and I’ve gotten pretty excited with everything I’ve done under the hood. Now I’m moving onto exterior.

I am currently replacing the stock premium wheels which I believe are 19x8.5, with new 19x9.5 wheels all around. Anyone know a good tire size to go with and if I am going to have to do any additional work?
Depends on your goals and use of your car. My S550 is track only, but my S197 is street driven. On my street Mustang, I installed the factory wheels and tires from my S550. But only after checking that they were not bigger than the optional factory wheels and tires available on my S197! Ford puts a lot of rubber under our Mustangs and due to wheel and tire "mistakes" I've made on earlier Mustangs... I no longer go beyond OEM.
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2020 Magnetic HPP EcoBoost
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Hello everyone, this is my first build and I’ve gotten pretty excited with everything I’ve done under the hood. Now I’m moving onto exterior.

I am currently replacing the stock premium wheels which I believe are 19x8.5, with new 19x9.5 wheels all around. Anyone know a good tire size to go with and if I am going to have to do any additional work?
My 2020 HPP with handling package came stock with 19x9.5 all corners and the tires were 265/40/19s

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I have a square setup 275/40/19 tires on 19X9.5" wheels with a 35mm offset. They fit perfectly.

You can't just put 275/40/19 tires on any 19" wheel. There is a minimum and maximum wheel width for a given tire size. There is also an offset required, offset being the movement in or out of the mounting hub from the centerline of the wheel. Have the wrong offset and this wide of tire will not fit at all as the outside of the fender well will crash into the tire when the suspension compresses. The tire size I have will also fit on a 10" wide wheel too, but changing the wheel width would likely change the offset require and so on. It goes on and on so there is no simple answer to your question.

I'm sure that there are people way smarter than me that can manually calculate all this stuff, but the simplest thing to do is to use a wheel size and tire calculator on one of the sites like American Muscle and just buy from them as you can skip all the calculations......find the wheel style you like and see if it is available in a size that will fit the tires size you want and you are done because they guarantee the combination will fit your car. I'm not recommending American Muscle as they screw up orders and make it hell to get straightened out, BUT they have the perfect fitment guide where you input you car details, model year and so forth, and they will automatically load what fits and you go from there. With any of these places, I STRONGLY recommend that you pay ONLY with a credit card otherwise you are likely **** out of luck if and when they screw your order up. Without the ability to dispute the charge, you have zero bargaining power and from my experience they don't give a flying F about whether your order is filled correctly or not once they have your money.
 

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Discussion Starter · #6 ·
I have a square setup 275/40/19 tires on 19X9.5" wheels with a 35mm offset. They fit perfectly.

You can't just put 275/40/19 tires on any 19" wheel. There is a minimum and maximum wheel width for a given tire size. There is also an offset required, offset being the movement in or out of the mounting hub from the centerline of the wheel. Have the wrong offset and this wide of tire will not fit at all as the outside of the fender well will crash into the tire when the suspension compresses. The tire size I have will also fit on a 10" wide wheel too, but changing the wheel width would likely change the offset require and so on. It goes on and on so there is no simple answer to your question.

I'm sure that there are people way smarter than me that can manually calculate all this stuff, but the simplest thing to do is to use a wheel size and tire calculator on one of the sites like American Muscle and just buy from them as you can skip all the calculations......find the wheel style you like and see if it is available in a size that will fit the tires size you want and you are done because they guarantee the combination will fit your car. I'm not recommending American Muscle as they screw up orders and make it hell to get straightened out, BUT they have the perfect fitment guide where you input you car details, model year and so forth, and they will automatically load what fits and you go from there. With any of these places, I STRONGLY recommend that you pay ONLY with a credit card otherwise you are likely **** out of luck if and when they screw your order up. Without the ability to dispute the charge, you have zero bargaining power and from my experience they don't give a flying F about whether your order is filled correctly or not once they have your money.
Thank you so much for the information, I checked out American muscle and it did say that 275/40/19 would fit my 19 Ecoboost! Now I guess I would begin tire shopping now. But when I have the wheels and tires installed do I tell them I want a specific offset such as yours since yours worked so well or would I just let them handle that? I ask because the shop I am currently going to works on almost nothing but mustangs of all trims, just curious I guess.
 

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I'm not sure that I understand your question. The wheels are made with specific offsets, it's not something the shop does at install. So if you already have wheels purchased, you may not be able to put the tire size you want on those specific wheels unless the offset just happens to be correct. That's why it is easiest to just order a tire and wheel package from somewhere like American Muscle as the specific combination is guaranteed to fit. They'll ship them to you and you can install yourself or take to a shop and have done...you can get the tires mounted, balanced and shipped already on the wheel ready to install on your car.

Again, if you already bought wheels, you need to know the offset of those specific wheels, to know what range of tires sizes will work on your car. If you are going to a Mustang oriented shop, they should be able to help you figure it out.
 

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I have a PP and have 275 35s on the stock 19s
 
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Discussion Starter · #9 ·
I'm not sure that I understand your question. The wheels are made with specific offsets, it's not something the shop does at install. So if you already have wheels purchased, you may not be able to put the tire size you want on those specific wheels unless the offset just happens to be correct. That's why it is easiest to just order a tire and wheel package from somewhere like American Muscle as the specific combination is guaranteed to fit. They'll ship them to you and you can install yourself or take to a shop and have done...you can get the tires mounted, balanced and shipped already on the wheel ready to install on your car.

Again, if you already bought wheels, you need to know the offset of those specific wheels, to know what range of tires sizes will work on your car. If you are going to a Mustang oriented shop, they should be able to help you figure it out.
I guess my question to make sense out of it, is that American Muscle says that 275/40/19 would fit on the car. So should I just buy one of the sets of tires that was recommended with the wheels originally? I’m saving up for nice tires which is why I didn’t buy the set, and the wheels were on a nice discount.
 

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I guess my question to make sense out of it, is that American Muscle says that 275/40/19 would fit on the car. So should I just buy one of the sets of tires that was recommended with the wheels originally? I’m saving up for nice tires which is why I didn’t buy the set, and the wheels were on a nice discount.
I don't think I can help you.
 

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ok, @Dean Prado have you read all of the other threads on tire size yet?

When you buy wheels, this is where you look at offset. A Wheel will have three numbers you need to know before buying tires to put on them.
1. Diameter - ecoboost Mustangs can come from the factory with anything from 17" to 20" wheels.
2. Width - ecoboost Mustangs can come with anything from 7" wide wheels to 9.5" wide ones. If you pick up something from the GT side of the family they could be even wider.
3. Offset - This is going to depend on how wide the wheels are. The narrowest wheels from the factory may have a higher offset than the wider ones you want to get. This is where you need to look at what the Mustang parts places do, they've put in a lot of time into what works.

Any wheel that fits an S550 Mustang will fit on our cars. It doesn't matter if it was designed for an ecoboost or a GT. When it comes to some of the factory wheels for GT350, GT500, Mach1, etc, may need some investigation, because those cars have some different suspension setups. If you radically change your suspension with lowering springs, or other elements, it can change what fits, so more research and more reading on the topic will always serve you better.

While tire shops may not like to do it, you can convince them to stuff almost any tire on the 9" wide Performance Pack wheels. I have 285/35R19 Bridgestones on mine. I don't drive on those daily, as they're really soft tires for autocross and track. Normally i would say, yes the widest tire for a 9" wide wheel would be 275, but as stated, you can get a 285 on them.

All tire manufacturers will give specifications on what size wheel is needed to fit specific size tires. This is really important when it comes to low profile tires like we run on a modern Mustang. trying to squeeze too wide of a tire on too narrow of a wheel can cause problems. The reverse is also true, and this is where you'll see the stance crowd stretch 205/50 tires on a 10" wide wheel. I don't recommend it, but it's one way to go.

Believe it or not, these green wheels are the stock PP wheels with a coat of paint and those Bridgestones.



My daily wheels are 19x9.5 +35 offset. I run 285/35R19 Firestone Firehawk Indy500 tires on them. They fit like a dream. I prefer the slightly wider 285 tires to fill the wheel well over the 275.



I really feel like I write this post at least four times a year...
 
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ok, @Dean Prado have you read all of the other threads on tire size yet?

When you buy wheels, this is where you look at offset. A Wheel will have three numbers you need to know before buying tires to put on them.
1. Diameter - ecoboost Mustangs can come from the factory with anything from 17" to 20" wheels.
2. Width - ecoboost Mustangs can come with anything from 7" wide wheels to 9.5" wide ones. If you pick up something from the GT side of the family they could be even wider.
3. Offset - This is going to depend on how wide the wheels are. The narrowest wheels from the factory may have a higher offset than the wider ones you want to get. This is where you need to look at what the Mustang parts places do, they've put in a lot of time into what works.

Any wheel that fits an S550 Mustang will fit on our cars. It doesn't matter if it was designed for an ecoboost or a GT. When it comes to some of the factory wheels for GT350, GT500, Mach1, etc, may need some investigation, because those cars have some different suspension setups. If you radically change your suspension with lowering springs, or other elements, it can change what fits, so more research and more reading on the topic will always serve you better.

While tire shops may not like to do it, you can convince them to stuff almost any tire on the 9" wide Performance Pack wheels. I have 285/35R19 Bridgestones on mine. I don't drive on those daily, as they're really soft tires for autocross and track. Normally i would say, yes the widest tire for a 9" wide wheel would be 275, but as stated, you can get a 285 on them.

All tire manufacturers will give specifications on what size wheel is needed to fit specific size tires. This is really important when it comes to low profile tires like we run on a modern Mustang. trying to squeeze too wide of a tire on too narrow of a wheel can cause problems. The reverse is also true, and this is where you'll see the stance crowd stretch 205/50 tires on a 10" wide wheel. I don't recommend it, but it's one way to go.

Believe it or not, these green wheels are the stock PP wheels with a coat of paint and those Bridgestones.



My daily wheels are 19x9.5 +35 offset. I run 285/35R19 Firestone Firehawk Indy500 tires on them. They fit like a dream. I prefer the slightly wider 285 tires to fill the wheel well over the 275.



I really feel like I write this post at least four times a year...
You suggested to read the other threads on this beat to death subject. I'm not sure why I had to answer......Thanks for all you do moderating this site and for all the patience you put forth.
 
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