245/40 or 275/35????

crazeflier07 · **245/40 or 275/35????**

What would be the difference? Is the 245 slimer in profile than the 275? Or is the 275 fat like a stock tire? Does the 40 mean that the tire sticks out farther then the lip of the rim or is 35 flush with the rim lip? I think I was running like 225/30/17 on the old cobra rims I was running before and they looked really really really small and I felt every bump bad. Thanks for the help.
~Jon~

**bbunt302** · **Re: 245/40 or 275/35????**

225/30/17???

The first number is the width in millimeters. The second number is a percentage. You multiply that number times the percentage to get the sidewall height. I suppose you know what the third is.

So, a 225/30/17 is going to be a very short tire. 225 mm * .30 = 67.5 mm of sidewall height. Multiply that by 2 (for top and bottom), convert to inches, and add to your wheel height to get the overall height in inches.

You want to run the equivalent of about a 25.6" tire for a 79-04 Mustang.

lowflyn · **Re: 245/40 or 275/35????**

To give you perspective, I'm running 275/35-18 tires all the way around, they turn 814 revolutions per mile. My stock tires, 225/55-16 turn 810 revolutions per mile. This was the closest I could come for a tire to fit a 18x9 wheel and keep the speedometer close.

What is the width of the wheels you are using.

**SpectorV** · **Re: 245/40 or 275/35????**

yea the middle number is the percent height, the percent the sidwall is of the tread width... yes its odd but its how they do it,also realize that every tire measures different, nitto for example is a very narrow tire... you would assume XXX mm is XXX mm but... the tire companies dont think so and some measure to different parts of the tire... they really need to regulate it.

**PureVenom** · **Re: 245/40 or 275/35????**


Quote: Originally Posted by SpectorV yea the middle number is the percent height, the percent the sidwall is of the tread width... yes its odd but its how they do it,also realize that every tire measures different, nitto for example is a very narrow tire... you would assume XXX mm is XXX mm but... the tire companies dont think so and some measure to different parts of the tire... they really need to regulate it.

How bout this...a 275 nitto is a 275...but the 315 is not...more like a 295/300 ish. They can't even keep it straight in their own branding.

crazeflier07 · **Re: 245/40 or 275/35????**


Quote: Originally Posted by lowflyn To give you perspective, I'm running 275/35-18 tires all the way around, they turn 814 revolutions per mile. My stock tires, 225/55-16 turn 810 revolutions per mile. This was the closest I could come for a tire to fit a 18x9 wheel and keep the speedometer close. What is the width of the wheels you are using.

Well if I cant fit a 9 back there I will probably be running a 18x8.5 tire. I want to have a low profile tire but I would like to protect the lip of the rim a little bit.
~Jon~

**SpectorV** · **Re: 245/40 or 275/35????**

why cant you fit a 9 in the back many have ran 11s

lowflyn · **Re: 245/40 or 275/35????**

I understand that you are going back on air, but for the sake of the wheels I would run at least a 265 on a 9 inch wide wheel, and I'd recommend running a 275. Anything smaller than a 265 and you would increase your chances of damaging the lip of the wheel.

As far as low profile, how low are you wanting to go? Like I say, I have 35 series on mine and that's as low as I'll ever go on a car I believe. It's enough sidewall to protect the wheels but still small enough to look good to me.

3.3Liters4Fun · **Re: 245/40 or 275/35????**

This might help, Its a GUI tire size calculator

Tire size calculator

Should make it so you can compare different size tires

crazeflier07 · **Re: 245/40 or 275/35????**


Quote: Originally Posted by SpectorV why cant you fit a 9 in the back many have ran 11s

When I get the 18s that I want the rim is going to be tucking up into the wheel well. The problem is the fender lip and the clearance I need to get under without hitting the body, rim, or the chance of digging into the tire. I would love to run a 11 back there but I would be doing some more cutting then I am ready to do right now.
~Jon~

crazeflier07 · **Re: 245/40 or 275/35????**


Quote: Originally Posted by lowflyn I understand that you are going back on air, but for the sake of the wheels I would run at least a 265 on a 9 inch wide wheel, and I'd recommend running a 275. Anything smaller than a 265 and you would increase your chances of damaging the lip of the wheel. As far as low profile, how low are you wanting to go? Like I say, I have 35 series on mine and that's as low as I'll ever go on a car I believe. It's enough sidewall to protect the wheels but still small enough to look good to me.

I'm probably just like you with wanting to protect the rim and still have a nice look. I guess what I'll get is like a 275/35/18 wheel so that I still have some tire past the lip of the rim and have enough tire to give a little sidewall. I've been going up to cars all weekend and looking at the type of tires they have so I could get an idea of what size I want with the right width and sidewall height. Wish tire company websites could show you the different tires on the car with the different sizes that you could choose to put on.
~Jon~