Wheel/tire questions; please educate me

[doodguy]

Hello,

I am running a 2015 Roush Supercharged mustang GT with 255 tires all the way around. I want to eventually put some wider tires on. That said can someone answer the following questions please?

1) Wheel height; what is the difference between 18, 19, 20 inch rims? Is it just the look?

2) The tire fatness like 275x40x17 Is there any advantage to a low profile vs. higher profile design? I favor the higher profile because in my head I imagine it is a smoother ride?

3) Width: What is the widest tire I can fit on this car? 305? 315?

4) Should I stagger the tires? I understand this reduces tire life, but what are the advantages of staggering?

5) Anything else I need to know? I'm pretty sure I need 9.5" rims, are there different hardness levels, or what is there to know?

Thank you

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[Need4SpeedMotors]

Hello,

I am running a 2015 Roush Supercharged mustang GT with 255 tires all the way around. I want to eventually put some wider tires on. That said can someone answer the following questions please?

1) Wheel height; what is the difference between 18, 19, 20 inch rims? Is it just the look?

2) The tire fatness like 275x40x17 Is there any advantage to a low profile vs. higher profile design? I favor the higher profile because in my head I imagine it is a smoother ride?

3) Width: What is the widest tire I can fit on this car? 305? 315?

4) Should I stagger the tires? I understand this reduces tire life, but what are the advantages of staggering?

5) Anything else I need to know? I'm pretty sure I need 9.5" rims, are there different hardness levels, or what is there to know?

Thank you

Lets start from the top for you brotha !

1. The difference is a increase in diameter by 1" fair enough.

2. The profile of the tire is adjusted based on the diameter of the wheel, for instance 19" we use between a 40 profile and a 35 profile depending on brand ( oversized or not oversized tires) and width. Either way for the S550 you can get a nice beefy profile tire on all diameter wheels.

3. depending on the wheel ( width and offset and brand of tire) you can easily put up to a 315 on the backend, some camber may be needed to be adjusted depending once again on diameter, lowered and such. I have put a 325 on the back of one as a test fit and it worked but once again depends on brand of the tire and such.

4. The choice is yours at the end, depending on the wheel design you go with you can run a square fitment and or staggered, the wider the front is the better handling you receive and overall performance, I like to go as wide as I can for looks ( deeper concave wheels front and rear) and beefier tires which help the car overall.

5. if you have any other questions just ask or you can even pm me if you want, width once again based on the design and brand of wheel model you go with.

 

[GoBlues38]

274/40-20

1st number = the width of the tire in millimeters

2nd number is the height of the tire sidewall as a percentage of width (305/40 will be taller than a 275/40 tire)

3rd number = rim size

..... to answer your questions....
1 = yes, mostly just the look, but each car is set up to have a certain size diameter wheel and tire combo to fill up the fender. so 1 and 2 are related

2 = if you have a smaller rim, you have to have a taller tire to fill the fender. yes taler tire may have a softer ride, and wheels will be less prone to bending, but a lower profile tire in most cases will have less sidewall deflection and be a better handling tire in corners (in general)

3 = depends on the rim width. i defer to others as i have not tried to fit a wide tire in this car

4 = a square set up (all same size) generally looks better to most, but a staggered set up has performance advantages at the cost of not being able to rotate tires.

5 = you get what you pay for. cheaper wheels generally are softer alloys and more prone to bending when you hit a pot hole. advice from my experience is not not have a low profile tire with a cheaper wheel, you will just bend them after your first pothole. i learned that lesson years ago.

 

[doodguy]

Thanks for the tips guys!!!!

In regards to the staggered setup performance advantage, I imagine it is less rolling resistance in the front so helps go straight faster? If I went with a 315 in the front vs. a 275 would it be a lot less rolling resistance/noticeable? I don't drag race my car, just little romps on the gas pedal here and there when my foot gets twitchy or some friends ask me to. For the most part I cruise around. I'm shooting for around 750 crank hp this weekend is why I'm interested in the wider tires.

 

[Lowrider]

Lets start from the top for you brotha !

1. The difference is a increase in diameter by 1" fair enough.

2. The profile of the tire is adjusted based on the diameter of the wheel, for instance 19" we use between a 40 profile and a 35 profile depending on brand ( oversized or not oversized tires) and width. Either way for the S550 you can get a nice beefy profile tire on all diameter wheels.

3. depending on the wheel ( width and offset and brand of tire) you can easily put up to a 315 on the backend, some camber may be needed to be adjusted depending once again on diameter, lowered and such. I have put a 325 on the back of one as a test fit and it worked but once again depends on brand of the tire and such.

4. The choice is yours at the end, depending on the wheel design you go with you can run a square fitment and or staggered, the wider the front is the better handling you receive and overall performance, I like to go as wide as I can for looks ( deeper concave wheels front and rear) and beefier tires which help the car overall.

5. if you have any other questions just ask or you can even pm me if you want, width once again based on the design and brand of wheel model you go with.

Wider front as opposed to wider rear...was that a typo?

OP tire choice is also going to be crucial. What brands are you looking at?

 

[mustang_guy]

Tall sidewall tires also have better traction from a stop then the 30 series. Say 40-45 for example. Its the reasons people run tall sidewall tires for drag racing (which a lot of times are higher then 45). But thinner series has less sidewall flex for handling. Something to consider too. Pick your rim and tire size based off your plans for the car.

 

[doodguy]

Tall sidewall tires also have better traction from a stop then the 30 series. Say 40-45 for example. Its the reasons people run tall sidewall tires for drag racing (which a lot of times are higher then 45). But thinner series has less sidewall flex for handling. Something to consider too. Pick your rim and tire size based off your plans for the car.

Yep; I probably wont' buy til early to mid next year; just doing some preliminary research trying to learn the pros/cons of the different options.

And yes; typo; I meant wider rears for stagger. So I have 19" rims now I think I'll stay with the 19's, and do like 315x40x19's all around? Car will mostly be a street driver. I dunno if I'll ever feel up to having a roll cage installed, so it won't get many if any drag strip days because they won't let me run without roll cage.

 

[mustang_guy]

Yep; I probably wont' buy til early to mid next year; just doing some preliminary research trying to learn the pros/cons of the different options.

And yes; typo; I meant wider rears for stagger. So I have 19" rims now I think I'll stay with the 19's, and do like 315x40x19's all around? Car will mostly be a street driver. I dunno if I'll ever feel up to having a roll cage installed, so it won't get many if any drag strip days because they won't let me run without roll cage.

I wasn't the one that mentioned the width. Wrong quote on that part.
The sidewall height also applies to street racing too . Doesn't have to be just the strip. If you don't street race, nothing to consider, 19s it is for you.

 

[Schu]

One thing I didn't notice from the above posts is that the aspect ratio number, the 315/40/18, is directly related to the tires width.

That is... a 40 series tires sidewall height (315/40/18) is 40% of it's width. that means a 315/40/18 has a taller sidewall than a 275/40/18 tire.

Also... the first number is in millimeters so that:
A 315/40/18 tire has a width of 315mm and a sidewall height of 189mm
A 275/40/18 tire has a width of 275mm and a sidewall height of 165mm
there you can see not all 40 series tires have similar sidewall heights.

 

[Need4SpeedMotors]

you dont want to go any wider then a 285 upfront depending on the wheel and offset

 

[CrazedAntelope]

Just wanted to elaborate on the tall vs thin sidewall in regards to handling...

I've always wondered why so many people think thin sidewalls automatically equals improved handling. You pretty much always see race cars and dedicated track cars with smaller diameter rims and thick sidewalls. Here is what I have found from my research:

1. Thin sidewall w/ a larger diameter wheel (20") = less sidewall deflection = improved steering feel and response.
2. Thick sidewall w/ a smaller diameter wheel (18' or 19") = usually less over all wheel and tire weight = less unsprung weight... many benefits there
3. Thick sidewall w/ a smaller diameter wheel = more progressive feel when you're losing traction... I assume this makes it easier to find and stay on the limit of the tire
4. Thick sidewall w/ a smaller diameter wheel = smoother ride on bumpy roads

Oh also a square setup is good for dialing out understeer.

 

[Need4SpeedMotors]

Just wanted to elaborate on the tall vs thin sidewall in regards to handling...

I've always wondered why so many people think thin sidewalls automatically equals improved handling. You pretty much always see race cars and dedicated track cars with smaller diameter rims and thick sidewalls. Here is what I have found from my research:

1. Thin sidewall w/ a larger diameter wheel (20") = less sidewall deflection = improved steering feel and response.
2. Thick sidewall w/ a smaller diameter wheel (18' or 19") = usually less over all wheel and tire weight = less unsprung weight... many benefits there
3. Thick sidewall w/ a smaller diameter wheel = more progressive feel when you're losing traction... I assume this makes it easier to find and stay on the limit of the tire
4. Thick sidewall w/ a smaller diameter wheel = smoother ride on bumpy roads

Oh also a square setup is good for dialing out understeer.

very good info !

 

[Norm Peterson]

Just wanted to elaborate on the tall vs thin sidewall in regards to handling...

I've always wondered why so many people think thin sidewalls automatically equals improved handling. You pretty much always see race cars and dedicated track cars with smaller diameter rims and thick sidewalls. Here is what I have found from my research:

1. Thin sidewall w/ a larger diameter wheel (20") = less sidewall deflection = improved steering feel and response.
2. Thick sidewall w/ a smaller diameter wheel (18' or 19") = usually less over all wheel and tire weight = less unsprung weight... many benefits there
3. Thick sidewall w/ a smaller diameter wheel = more progressive feel when you're losing traction... I assume this makes it easier to find and stay on the limit of the tire
4. Thick sidewall w/ a smaller diameter wheel = smoother ride on bumpy roads

Oh also a square setup is good for dialing out understeer.

Race cars typically have the allowable wheel diameters specified in the rules for whatever series they are run in. For example, NASCAR still runs 15" wheels, so you need quite a lot of tire sidewall to achieve 200 mph capability.

#3 - with a thick-sidewall arrangement you'll generally lose lateral grip at a lower speed / lower lateral g's, where things won't happen quite as suddenly.

But the thin-sidewall setup is likely to be more sensitive to suspension geometry and static alignment settings especially as the actual tread widths get wider.


Norm

 

[Norm Peterson]

Wider front as opposed to wider rear...was that a typo?

I didn't see this getting answered yet . . .

Wider front meaning adding more tire width up front than out back. Crudely because I'm not going to get into profiles and load capacities here - something like taking a GTPP from a 255-wide tire up front to a 275 while either leaving the rear tires at 275 or maybe moving them up to 285's. You're trying to add a little more front grip to more closely match the higher amount of rear grip that's there to begin with in any car that understeers (which is just about everything you can buy these days).


Norm

 

[Schu]

My god some of the information in here is just plain incorrect.

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