Are 215/40/17 size tires safe for speed on 17x8 rims?

[BLADDER92FOX]

I was wondering if the size 215/40/17 tire on my 17x8 bullit rims are safe for expressway speeds. My rears have 275/40/17, but i wanted to get low profile tires for the front.Should i get 225/40/17 or is it safe with 215/40/17.Please give me some feedback.

 

[Mavrick]

Why not go with stock width? 245/40's?

 

[iblue]

215/40/17 are not lower profile than 275/40/17. Lower profile tires would be 275/35/17. Tire measurements go width/height/interior diameter. I have run 205/40/17's on a 17x7.5" wheel before. But yes it's possible to run 215/40/17's on a 17x8" wheel. Reccomended size would be closer to 225/40/17 however.

 

[BLADDER92FOX]

Well right now i have 225/55/17 up front cause i got these rims with those tires on it. I'm just wondering if i'll be ok with 215/40/17 up front if i drive close to 130-140mph ,which i don't often but in case i ever do. Plus i go about 100mph alot sometimes on the fast freeway.

 

[iblue]

Well right now i have 225/55/17 up front cause i got these rims with those tires on it. I'm just wondering if i'll be ok with 215/40/17 up front if i drive close to 130-140mph ,which i don't often but in case i ever do. Plus i go about 100mph alot sometimes on the fast freeway.

Oh, ok, that makes more sense as to the lower profile stuff. As for the 130-140mph stuff, check the speed ratings on your tires you are going to purcahse. Here is a tire speed rating refrence:

Rating - Speed
S 180km/h or 112mph
T 190km/h or 118mph
U 200km/h or 125mph
H 210km/h or 130mph
V 240km/h or 149mph
W(ZR) 270km/h or 168mph
Y(ZR) 300km/h or 186mph
ZR Above 300km/h or 186mph

 

[1SLO306]

215/40/17 are not lower profile than 275/40/17. Lower profile tires would be 275/35/17. Tire measurements go width/height/interior diameter. I have run 205/40/17's on a 17x7.5" wheel before. But yes it's possible to run 215/40/17's on a 17x8" wheel. Reccomended size would be closer to 225/40/17 however.

actually the first to numbers has to do with the diameter. my 245/50/16(back) is taller then my 225/50/16(front) and tire makers are not always the same.

with 17x8's i would go 245/45/17

 

[RacEoHolic330]

Just to clarify, the first number is the width of the tire in millimeters, the second number is the height of the sidewall as a percentage of the width. So a 245/40 tire means that the sidewall is 40% of 245mm, or 98mm.

And personally, I wouldn't go any smaller than a 235 on an 8" wide wheel. Having a wider tire will provide more stability. Not only is is not very safe stretching a tire out like that, it will look increadibly stupid. Almost as stupid as driving your 14 year old car on the highway at over 100mph all the time.

 

[iblue]

actually the first to numbers has to do with the diameter. my 245/50/16(back) is taller then my 225/50/16(front) and tire makers are not always the same.

with 17x8's i would go 245/45/17

Then actually its still width/height/interior diameter. I did not state that the method used to calculate the numbers is not dependant on the diameter. I only stated that the numbers represent width/height/interior diameter, which they do. And yes, you are absoltely correct and tire makers need to use a better method for sizing, IMO.

 

[1SLO306]

Then actually its still width/height/interior diameter. I did not state that the method used to calculate the numbers is not dependant on the diameter. I only stated that the numbers represent width/height/interior diameter, which they do. And yes, you are absoltely correct and tire makers need to use a better method for sizing, IMO.

basicly u did or sounds like anyways

215/40/17 are not lower profile than 275/40/17. Lower profile tires would be 275/35/17.

but its all good no need to stir up an arguement.

 

[BLADDER92FOX]

Well i made up my mind now,i asked around and i'm getting a 235-245/40/17tire instead. Thanx for all the info.

 

[Michael Yount]

Bladder - the important part of this post relative to your question is the SPEED RATING of the tire -- not so much the size of the tire. Although, with an 8" wide rim I'd go with a wider tire as you're going to. Also, the Stang is quite front heavy and understeers like a pig --- that smaller tire on the front only makes things worse. Besides that, the 215/40/17 is a full 2" shorter than a stock sized tire -- which probably looks quite goofy on a stock height car -- LOTS of space between tire and fender. You haven't gone low-rider on us with that Stang down in FL have you?

As for all the rest of the stuff -- here's how it works. The first number in the tire size is the SECTION WIDTH of the tire in millimeters when it's mounted on a proper width wheel. Section width is between the sidewalls -- not the tread width. The proper width wheel is one that is not more than 2" narrower than the section width of the tire. The second number in the tire is the aspect ratio. 35- 45 - 55- 60 -- think of these as percentages. You multiply the aspect ratio times the section width to get the height of the sidewall -- distance from the ground to the where the wheel starts.

So to calculate overall height of any tire - you convert the section width to inches by dividing it by 25.4 mm/in. Then you multiply that number by the aspect ratio to get sidewall height. 2X the sidewall height plus the wheel diameter gives you the height of the tire.

Stock Stang - 225/55/16 --- ((225/25.4) X .55 X 2) + 16= 25.75" tall

215/40/17 ----- ((215/25.4) X .4 X 2) + 17 = 23.7"

235/40/17 --- ((235/25.4) X .4 X 2) + 17 = 24.4"

Even that size is a full inch shorter than stock.

The proper height in a 17" tire with a 40-series aspect ratio is a 275/40/17 (25.7") -- however, that's a bit too wide a tire for an 8" rim. You really need a 9" wheel for that wide a tire. What you'd like for a 17"X8" wheel as Blake said is a 245/45/17" tire -- that's 25.7" tall too.

If you're serious about 130-140 mph speeds, then as iblue said -- you want at least a V-rated tire, regardless of the size.