Fitment advice: GT with progressive springs, daily driver with a little road course time

[DCBuckeye]

Hi all. I've been trying to scour previous posts and find myself having trouble finding advice that fits my situation. I'm basically a total noob at aftermarket wheels, but I understand enough to know that along with width there are issues around offset, but that's about it. I also am of the impression 10" wheels should be doable for me, but the tire online configurators I've found seem to not want to offer anything over 9 or 9.5". Anyway...

I've got a 2024 GT, without the performance pack, and am having Steeda progressive springs and stop the hop installed. This car is my daily driver, and gets taken to a road course maybe twice a year (nothing competitive, just having some fun).

What advice would y'all have for wheel and tire fitment? While I love the look of staggered, I'm thinking square may make more sense for me based on what I read about tire rotation and this also being my daily. Thanks.

Edit: Clarified inline the model year

Sponsored

 

[krisk]

Hi all. I've been trying to scour previous posts and find myself having trouble finding advice that fits my situation. I'm basically a total noob at aftermarket wheels, but I understand enough to know that along with width there are issues around offset, but that's about it. I also am of the impression 10" wheels should be doable for me, but the tire online configurators I've found seem to not want to offer anything over 9 or 9.5". Anyway...

I've got a GT, without the performance pack, and am having Steeda progressive springs and stop the hop installed. This car is my daily driver, and gets taken to a road course maybe twice a year (nothing competitive, just having some fun).

What advice would y'all have for wheel and tire fitment? While I love the look of staggered, I'm thinking square may make more sense for me based on what I read about tire rotation and this also being my daily. Thanks.

If you are wanting to do a square setup with the Steeda springs and use it as a daily driver with the same tire and wheel setup that you use on the track, then I personally wouldn't go any wider than a 285 tire, which would work well on a 10" wide wheel. If you choose wheels that fit the rear of the Mustang, then you should be able to run the same wheel up front using a spacer. The size spacer needed will be based on the rear wheel offset.

I'm running 295/30/19 square on an 11" wheel for track only use, and it requires more camber up front than you would really want to run on the street. I could run a 305 on my current wheels without an issue if I wanted to go wider.

A staggered setup is easier because you don't need a spacer, but then you are limited on rotating. However, if you don't use a directional tire, you can still rotate it right to left, which for track use would be helpful in evening out the wear from side to side even though you'll wear the front at back at different rates.

 

[AZ_Ryan]

^ this.

10" is the goldilocks for a squared setup if you're doing any track stuff.

SVE has several options in that size for the Mustang.

 

[Flyingtexan]

Following

 

[Jekyll_Hyde]

If you are wanting to do a square setup with the Steeda springs and use it as a daily driver with the same tire and wheel setup that you use on the track, then I personally wouldn't go any wider than a 285 tire, which would work well on a 10" wide wheel. If you choose wheels that fit the rear of the Mustang, then you should be able to run the same wheel up front using a spacer. The size spacer needed will be based on the rear wheel offset.

I'm running 295/30/19 square on an 11" wheel for track only use, and it requires more camber up front than you would really want to run on the street. I could run a 305 on my current wheels without an issue if I wanted to go wider.

A staggered setup is easier because you don't need a spacer, but then you are limited on rotating. However, if you don't use a directional tire, you can still rotate it right to left, which for track use would be helpful in evening out the wear from side to side even though you'll wear the front at back at different rates.

I’ve been trying to figure out this tire stuff lately, but am still learning. Can u explain why u need a spacer on a square setup and not staggered?

 

[AZ_Ryan]

I’ve been trying to figure out this tire stuff lately, but am still learning. Can u explain why u need a spacer on a square setup and not staggered?

I could be wrong, but I think he's referring to running a wide square set up. Like 11". For 10" I've never heard of needing a spacer.

 

[krisk]

I’ve been trying to figure out this tire stuff lately, but am still learning. Can u explain why u need a spacer on a square setup and not staggered?

I could be wrong, but I think he's referring to running a wide square set up. Like 11". For 10" I've never heard of needing a spacer.

The need for a spacer is determined by the backspacing on the wheel as well at the tire width. When you buy a staggered setup designed for the S550/S650, the offset (and therefore backspacing) is set where the wheels fit inside the fender and don’t rub the shock or strut. If you put the same wheel and tire on the front and back of a Mustang, the front tire will be about 1” closer to the strut than the rear wheel is to the shock in the back. That is to say the rear allows for around 1” more backspacing than the front.

There are some rear wheels that you can run in the front without a spacer and they will certainly fit, but they will likely be tucked back under the fender more than normal and look somewhat odd. Not to say there’s anything wrong if you like the look, but it’s not what most people are going for.

A front spacer allows you to run the same wheel in the front and back and have the amount of tuck under the fender be similar. Adding a spacer has the same effect as running a wheel with less offset. A 52mm positive offset wheel with a 25mm spacer would be just like running a wheel with a 27mm offset. However, when you go to certain widths, such as 11” wheels, you start having to increase the negative camber up front to keep the tire from contacting the fender. This works well for a track car, but is not ideal for even wear on a street car.

There are some manufacturers, like Alex, that make the same diameter and width wheel for both the front and back. They make a 19x11 ET52 for the rear and a 19x11 ET26 for the front. The wheels are the same dimensions, but the front has 1” less offset/backspacing. I run the ET52 on all corners and use a spacer up front rather than buying the front wheels with the correct offset. Doing so allows me to rotate all four tires. If I had the front and rear with different offsets and no spacers I would not be able to rotate front to back even though the tires are exactly the same size. The ET52 would contact the strut if mounted up front and the ET26 would contact the fender if mounted in the rear, which is why they could not be rotated front to back.

 

[Jekyll_Hyde]

That makes sense because when I lowered my 25 GT with progressive springs my front wheels are pushed under the fender. I didn’t realize there’s a 1 inch difference front to back. Now I know how to fix it!

Thanks for the explanation!

 

[Jekyll_Hyde]

The need for a spacer is determined by the backspacing on the wheel as well at the tire width. When you buy a staggered setup designed for the S550/S650, the offset (and therefore backspacing) is set where the wheels fit inside the fender and don’t rub the shock or strut. If you put the same wheel and tire on the front and back of a Mustang, the front tire will be about 1” closer to the strut than the rear wheel is to the shock in the back. That is to say the rear allows for around 1” more backspacing than the front.

There are some rear wheels that you can run in the front without a spacer and they will certainly fit, but they will likely be tucked back under the fender more than normal and look somewhat odd. Not to say there’s anything wrong if you like the look, but it’s not what most people are going for.

A front spacer allows you to run the same wheel in the front and back and have the amount of tuck under the fender be similar. Adding a spacer has the same effect as running a wheel with less offset. A 52mm positive offset wheel with a 25mm spacer would be just like running a wheel with a 27mm offset. However, when you go to certain widths, such as 11” wheels, you start having to increase the negative camber up front to keep the tire from contacting the fender. This works well for a track car, but is not ideal for even wear on a street car.

There are some manufacturers, like Alex, that make the same diameter and width wheel for both the front and back. They make a 19x11 ET52 for the rear and a 19x11 ET26 for the front. The wheels are the same dimensions, but the front has 1” less offset/backspacing. I run the ET52 on all corners and use a spacer up front rather than buying the front wheels with the correct offset. Doing so allows me to rotate all four tires. If I had the front and rear with different offsets and no spacers I would not be able to rotate front to back even though the tires are exactly the same size. The ET52 would contact the strut if mounted up front and the ET26 would contact the fender if mounted in the rear, which is why they could not be rotated front to back.

One more question, with 20” x 9” wheel, I can’t add much sidewall bc the wheel is tall and I can’t go much wider bc the wheel isn’t wide enough. So the best I can do is go from 265/35/20 to 285/35/20.
I’m I thinking about that right?

 

[AZ_Ryan]

One more question, with 20” x 9” wheel, I can’t add much sidewall bc the wheel is tall and I can’t go much wider bc the wheel isn’t wide enough. So the best I can do is go from 265/35/20 to 285/35/20.
I’m I thinking about that right?

If you're looking for more sidewall, that change is hardly worth it.

 

[AZ_Ryan]

The need for a spacer is determined by the backspacing on the wheel as well at the tire width. When you buy a staggered setup designed for the S550/S650, the offset (and therefore backspacing) is set where the wheels fit inside the fender and don’t rub the shock or strut. If you put the same wheel and tire on the front and back of a Mustang, the front tire will be about 1” closer to the strut than the rear wheel is to the shock in the back. That is to say the rear allows for around 1” more backspacing than the front.

There are some rear wheels that you can run in the front without a spacer and they will certainly fit, but they will likely be tucked back under the fender more than normal and look somewhat odd. Not to say there’s anything wrong if you like the look, but it’s not what most people are going for.

A front spacer allows you to run the same wheel in the front and back and have the amount of tuck under the fender be similar. Adding a spacer has the same effect as running a wheel with less offset. A 52mm positive offset wheel with a 25mm spacer would be just like running a wheel with a 27mm offset. However, when you go to certain widths, such as 11” wheels, you start having to increase the negative camber up front to keep the tire from contacting the fender. This works well for a track car, but is not ideal for even wear on a street car.

There are some manufacturers, like Alex, that make the same diameter and width wheel for both the front and back. They make a 19x11 ET52 for the rear and a 19x11 ET26 for the front. The wheels are the same dimensions, but the front has 1” less offset/backspacing. I run the ET52 on all corners and use a spacer up front rather than buying the front wheels with the correct offset. Doing so allows me to rotate all four tires. If I had the front and rear with different offsets and no spacers I would not be able to rotate front to back even though the tires are exactly the same size. The ET52 would contact the strut if mounted up front and the ET26 would contact the fender if mounted in the rear, which is why they could not be rotated front to back.

Thank you for the correction. That makes perfect sense. I forgot about the offset difference front to back.

 

[krisk]

One more question, with 20” x 9” wheel, I can’t add much sidewall bc the wheel is tall and I can’t go much wider bc the wheel isn’t wide enough. So the best I can do is go from 265/35/20 to 285/35/20.
I’m I thinking about that right?

On a 20x9 wheel 285/35/20 could be mounted, but it would likely be wider than the recommended by the manufacturer for your wheel width.

You also have to consider if it will fit in the wheel well without rubbing. The OE Ford wheel looks to be a 42.5 offset. Therefore the stock tire is approximately 175mm from the font of the hub to the inside of the tire and 90mm to the outside of the tire (tire width divided by 2 plus offset for inside distance and minus offset for outside distance). If you go to a 285 tire, the inside is now 185mm and the outside is 100mm. Additionally, the tire will be slightly taller which will affect fitment. These numbers are ball park figures because two brands of 285 tires will have slightly different actual dimensions as well as a 285 mounted on a 9” wheel will be narrower than when mounted on a 10.5” wheel.

I don’t know exact numbers of what will fit because it will vary based on the height of the tire, but I did a lot of calculations when I was working on my tire setup. With my setup I have a 295/30/19 on a 19x11 ET52 and run a 28mm spacer up front. I have approximately 8mm of clearance between the inside of the tire and the strut, and it is about 172mm from the hub to the inside of the tire (295/2+52.5-28). If I have 8mm of clearance, then my total hub to inside of the tire clearance is a maximum of 180mm with my 26” tall tire. The tire height really is more of an issue with outside distance from the hub because of having to clear the fender or with scrubbing the inside wheel well at full steering lock, but I mention it just so you know tire height will affect fitment. So I’ve measured about 180mm of inside clearance on my car. If you go to a 285 wide tire you’ll be at 185mm inside. I’m afraid that tire may rub the strut. That said, all of these numbers are approximate, so actual fitment could vary a few mm which can affect fitment, and I also don’t know if the non-PP cars have different clearances which would mean the measurements I’ve taken on my car may be different.

Before you decide to go to a 285 on the OE wheels, you need to either 1. Find if anyone else has used those tires/wheels on a car with the same suspension you have, or 2. Measure the clearance of your current tires to make sure adding the extra 10mm inside and outside as well as some extra height won’t result in contact with the suspension or fender including while turning.

 

[Jekyll_Hyde]

If you're looking for more sidewall, that change is hardly worth it.

On a 20x9 wheel 285/35/20 could be mounted, but it would likely be wider than the recommended by the manufacturer for your wheel width.

You also have to consider if it will fit in the wheel well without rubbing. The OE Ford wheel looks to be a 42.5 offset. Therefore the stock tire is approximately 175mm from the font of the hub to the inside of the tire and 90mm to the outside of the tire (tire width divided by 2 plus offset for inside distance and minus offset for outside distance). If you go to a 285 tire, the inside is now 185mm and the outside is 100mm. Additionally, the tire will be slightly taller which will affect fitment. These numbers are ball park figures because two brands of 285 tires will have slightly different actual dimensions as well as a 285 mounted on a 9” wheel will be narrower than when mounted on a 10.5” wheel.

I don’t know exact numbers of what will fit because it will vary based on the height of the tire, but I did a lot of calculations when I was working on my tire setup. With my setup I have a 295/30/19 on a 19x11 ET52 and run a 28mm spacer up front. I have approximately 8mm of clearance between the inside of the tire and the strut, and it is about 172mm from the hub to the inside of the tire (295/2+52.5-28). If I have 8mm of clearance, then my total hub to inside of the tire clearance is a maximum of 180mm with my 26” tall tire. The tire height really is more of an issue with outside distance from the hub because of having to clear the fender or with scrubbing the inside wheel well at full steering lock, but I mention it just so you know tire height will affect fitment. So I’ve measured about 180mm of inside clearance on my car. If you go to a 285 wide tire you’ll be at 185mm inside. I’m afraid that tire may rub the strut. That said, all of these numbers are approximate, so actual fitment could vary a few mm which can affect fitment, and I also don’t know if the non-PP cars have different clearances which would mean the measurements I’ve taken on my car may be different.

Before you decide to go to a 285 on the OE wheels, you need to either 1. Find if anyone else has used those tires/wheels on a car with the same suspension you have, or 2. Measure the clearance of your current tires to make sure adding the extra 10mm inside and outside as well as some extra height won’t result in contact with the suspension or fender including while turning.

THANKS for your help guys!! I agree AZ_Ryan, it’s not worth making the change. At 275 or 285 I won’t pick up much sidewall. I may just get diff tires, same size. I don’t love the Eagle F1s that came stock. And one day, I can get summer tires on 19” wheels and go bigger. The problem is I love the stock wheels.

Sponsored