Tire Wheel Size Question

[Edgemere]

Greetings,

I have Good Year F1 265/35R20 mounted on 20" wheels on all 4-corners, of my 2022 Mustang GT Premium. These wheels and tires came with my car from the factory. I want to lower my car .05" to maybe 1" with new lowering springs. I do want to keep my same wheels and tires.

Does my current wheel/tire set up take up more room in the wheel well then 19" wheels with similar tires? Are both 19" & 20" wheels with tires the same diameter but the 19" wheel shows more side wall of the tire? Have I explained this correctly? I am just concerned about lowing the car and having rubbing issues.

Happy Turkey Day.

Thanks, Edgemere

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[Corporate_Rebel]

Here you go, this site you can play with tire sizes and rims and it'll convert everything to height for you.

https://tiresize.com/height-calculator/

 

[Edgemere]

Wow! That is so cool. Thank you very much!

 

[Need4SpeedMotors]

Greetings,

I have Good Year F1 265/35R20 mounted on 20" wheels on all 4-corners, of my 2022 Mustang GT Premium. These wheels and tires came with my car from the factory. I want to lower my car .05" to maybe 1" with new lowering springs. I do want to keep my same wheels and tires.

Does my current wheel/tire set up take up more room in the wheel well then 19" wheels with similar tires? Are both 19" & 20" wheels with tires the same diameter but the 19" wheel shows more side wall of the tire? Have I explained this correctly? I am just concerned about lowing the car and having rubbing issues.

Happy Turkey Day.

Thanks, Edgemere

Hey this is Junior from N4SM. The 20" wheels are going to take up more room than the 19" wheels with the same tire size. You won't have any issues with rubbing on those wheel and tire sizes with 1 inch springs. These S550 Mustangs have a lot of room, we normally do a 20x10 285, 20x11 305 wheel and tire setup on these cars on 1 inch springs and have no rubbing issues.

 

[Edgemere]

Thanks

 

[NightmareMoon]

Hey this is Junior from N4SM. The 20" wheels are going to take up more room than the 19" wheels with the same tire size. You won't have any issues with rubbing on those wheel and tire sizes with 1 inch springs. These S550 Mustangs have a lot of room, we normally do a 20x10 285, 20x11 305 wheel and tire setup on these cars on 1 inch springs and have no rubbing issues.

Junior's wording is a little vague/confusing there.

Lets be a bit more specific. "Size" could mean one thing or another.

There is no "same tire size" A 265/35R20 is a different overall diameter than a 265/35R19, that's correct. because the tire size involves all three numbers.

265 is the width of the tread in mm, 35 is the sidewall size as a percentage of the tire width (so a 305/35 is a taller sidewall than 265/35 because 305*35% sidewall is bigger than 265*35%. Obviously the R19 or R20 is the wheel diameter.

So the overall diameter of the tire is the wheel radius plus that sidewall size.

In general, if you are picking a tire for a larger wheel diameter (19 to 20 for example), you'll look for tires which are a normal overall diameters for the car . Ideally the 20" wheel would use a tire with a slightly smaller sidewall than what you use on a 19" wheel so the overall package stays about the same size.... so you might drop from a 40% sidewall ratio to a 35% ratio or maybe a 30% ratio. Tires don't come in all possible size specs, so in many cases you might run a 285/35R20 on a 20" wheel and the same tire sidewall radio 285/35R19 on a 19" wheel because going down to a 285/30R19 would be a little too short for the car and while a 285/35R20 is a little large, its close enough to work. In many other cases you'll adjust your sidewall size when changing wheel diameters to keep that package as close as possible to what the car was designed to use. Same things happens if you change widths but keep the wheels the same diameter. If you're going from a narrow tire like a 245 R19 to a very wide tire like a 315 R19, you might look for smaller sidewall ratio on the wider tire for the same reason.. to keep the overall diameter in the normal range.

To answer your lowering question, if the wheel and tire fits fine, and you lower the car with lowering springs, then the new wheel and tire will still probably fit fine, because the standard lower part of the spring perch built into the shock sits above and clear of the tire, and the spring is above that, so a shorter spring doesn't affect the clearance to the spring perch. In some cases you might rub on a fender liner or something or the body fender on the outside might contact the tire if the tire sticks out too far due to wheel offset, but for normal wheel/tire fitments, this isn't often a major problem.

So lower away.

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