Going from 17's to 15's... What size tires?

Hey guys I currently have 17x7 inch wheels on my car with 205/40 tires. I am not entirely satisfied with how they look and I am looking to upgrade. The wheels that I want have two sizes that I am looking at 15x7 or 17x7.5 (they do not make them in 16"). I am leaning towards the 15’s but I don’t want my car to be much lower if possible. What size tires would you guys recommend for the 15" wheels so that I could stay close to the ride height I am at now? Also a friend told me that it is better for my brakes and suspension if I go with a wheel and tire size that is close to stock. One thing he said is that my rotors will spot more easily from heat if I have stock rotors and big wheels. Is this true? Also just in case you need to know I am running H&R Sport springs (1.8" drop) and KYB AGX struts.

the typical 205/50/15 would probably be your best bet.

205/50/15 is your freind

^^^ what they said

^^^ what she said that they said

Awesome sounds good. Thanks you guys!

That’s usually the most common, but don’t be afraid to use 195-55-15’s either if the particular tire you want only comes in that size (e.g. Dunlop Direzza Star Spec)

195/55/15 and 205/50/15 are the popular ones.

my choice would be 215/50/15 on a 7" wheel and is equal to stock.

[QUOTE=redtegra;2035918]195/55/15 and 205/50/15 are the popular ones.

my choice would be 215/50/15 on a 7" wheel and is equal to stock.[/QUOTE]

195-55-15 is slightly larger than stock, and 215-50-15 is slightly larger still. Should be an OK size, but not very common at all. In fact Tirerack only has ONE tire which comes in that size.

to the OP, the reason you dont want a tall tire is that it kills your performance

almost as much as those 17’s are killing your performance right now

1-2% difference is more then acceptable. plus 195-55-15 is stock gsr size and rs ls gs come with 195-60-14 on a DC. its all the same stuff. 225/50/15 is pretty nice also for a 7.5" rim with only a 2.8% difference. nice choice in race tires.

I realize that the difference is almost nothing. And in reality the variance from brand to brand and model to model is more than that even. The main issue w/ that tire size is that there’s almost nothing available in it. As a general rule you should pick your tire first and size second. If that tire doesn’t come in an acceptable size, then start looking at other options.

195-55-15 and 205-50-15 are the closest to stock. The former being slightly larger and the later being slightly smaller. You should feel that the 195’s are larger than stock. The car will sit a bit higher and you will notice this unless you’re completely oblivious. For me I’m glad for the small amount of ground clearance gained (if it’s a street car).

So if I go from what I have now (205/40/17) to what I am considering after all of your advice (205/50/15) will I notice a big difference in handling? I am just wondering if going from 205/40 to 205/50 would make a noticeable difference because the new tires will be slightly taller.

205/40/17 is taller than 205/50/15

Um… Actually I think its the other way around. Found this on tirerack.com
Here’s the link http://www.tirerack.com/tires/tiretech/techpage.jsp?techid=46

"Sidewall Aspect Ratio

Typically following the three digits identifying the tire’s Section Width in millimeters is a two-digit number that identifies the tire’s profile or aspect ratio.

P225/[B]50[/B]R16 91S

The 50 indicates that this tire size's sidewall height (from rim to tread) is 50% of its section width. The measurement is the tire's section height, and also referred to as the tire's series, profile or aspect ratio. [B]The higher the number, the taller the sidewall; the lower the number, the lower the sidewall.[/B] We know that this tire size's section width is 225mm and that its section height is 50% of 225mm. By converting the 225mm to inches (225 / 25.4 = 8.86") and multiplying it by 50% (.50) we confirm that this tire size results in a tire section height of 4.43". If this tire were a P225/70R16 size, our calculation would confirm that the size would result in a section height of 6.20", approximately a 1.8-inch taller sidewall."

i know what a f**king aspect ratio is

you are not taking into consideration the last number … your rim size

lets take for say bfg gsports

205/50/15=23.1" O.D.
205/40/17=23.5" O.D.

This question is far too vague and really you’re comparing too many variables.

Tires will “handle” better because of multiple factors:

  • rubber compound
  • sidewall stiffness
  • sidewall size
  • overall width
  • wheel size used

Additionally factors such as road conditions will change how a tire works. Some conditions will favor a larger profile, others a lower profile…etc.

[QUOTE=rallyrat427;2036556]i know what a f**king aspect ratio is

you are not taking into consideration the last number … your rim size

lets take for say bfg gsports

205/50/15=23.1" O.D.
205/40/17=23.5" O.D.[/QUOTE]

205/50/15 is a TIRE size am I correct? 205/40/17 is also a TIRE size yes? I am talking about tires here not the wheel and tire. I KNOW that the new wheels and tires will be a little bit shorter compared to my current wheels and tires. The tires that I will be using with the new wheels will have a slightly taller sidewall compared to what I have now. All I was trying to ask was how much different does a 50 series tire feel compared to a 40 series. I know that its a vague question and most of the answers I will get are opinions but I still want to know what people think.

ok sry i didnt realize you were asking how a little more rubber will feel.

it will grip the road better, more forgiving, and the ride will be more cush

ive ridden on both and the difference is night and day.

i might suggest you get someone to let you test drive their car with a 205/50/15 to see for yourself

^ That sounds like a good idea before I commit. Also thank you for your input, it has been helpful.