Tyres

[zei20l]

mythbusters isnt needed dude. some common sense and thought is all that is needed

the inner and outer circumference cant be changed. the inside being the rim size, ie 18". no matter how wide that rim is (within reason) its always 18"

the outside, the rolling diameter also remans the same because only the sidewall angle changes. it doesnt get longer, or shorter.

[Sunkist]

mythbusters isnt needed dude. some common sense and thought is all that is needed

the inner and outer circumference cant be changed. the inside being the rim size, ie 18". no matter how wide that rim is (within reason) its always 18"

the outside, the rolling diameter also remans the same because only the sidewall angle changes. it doesnt get longer, or shorter.

ahhhh lol but thats why the rolling diameter DOES change!

i give up. you win by default lol

[zei20l]

i dont want to win im trying to explain how it doesnt change

its also steel belted so it cant change.

only the sidewall angle can change to suit the rim width, yes the sidewall will flex. but thats half the reason why the tyres are filled with air.

[pipster11]

something would have to change as you get some pretty big angles when stretching tyres (big angles for engineering are anything over 5°)

but you are correct, the cylinder that makes the tyre cannot get that much smaller (but the rubber is elastic so it can contract a little bit)

so the sidewalls must either get dragged inwards on the rim or stretch a little

[Sunkist]

i dont want to win im trying to explain how it doesnt change

its also steel belted so it cant change.

only the sidewall angle can change to suit the rim width, yes the sidewall will flex. but thats half the reason why the tyres are filled with air.

based on the fact that the sidewall will physically stretch, and that rubber is softer that the steel belts, your right. makes sense now. if it was all rubber, physics simply wouldnt allow it.

[zei20l]

sidewalls are belted also, or strengthened with metal, but probably not as much to allow for flex for comfort, cornering, performance etc and also rim widths.

[Sunkist]

yeh but the overall thickness of the sidewall is thinner so it makes sense.

[zei20l]

the sidewal is designed to flex and distort. its normal for a tyre to do that (within reason) but when you stretch them, youre not allowing much movement. thus the tyre is 'firmer' and doesnt allow it to..... squirm?

[PN-Mad]

i know im goin to get flamed to death for saying it, but IMHO the federal 595 is highly over rated on a daily drive car. they are great for a weekend warrior or if u do ALOT of hard cornering. but for the daily commute i'd suggest something thats a little better in the wet and maybe wears better. i also agree with the other guys a 245 is pretty narrow on a 9.5 inch rim. id be goin a 265 to protect the rim a little better.

I'll be flamed with you then. The wife had a big accident on Bells Line of Road going down into Lithgow on these. Conditions were wet. Now, not saying that it was entirely the tyres fault, thats impossible and stupid to even consider that. However, I believe tyres play a big part of the dynamics of a car. Needless to say, post accident, Pirelli tyres went on all 4 corners.

I wouldn't consider buying them again, but thats just my opinion/experience.

[Raysboostin]

mythbusters isnt needed dude. some common sense and thought is all that is needed

the inner and outer circumference cant be changed. the inside being the rim size, ie 18". no matter how wide that rim is (within reason) its always 18"

the outside, the rolling diameter also remans the same because only the sidewall angle changes. it doesnt get longer, or shorter.

i understand what your saying. but they are right. try it for yourself. head down the tyre shop with an 8inch and a 9inch rim and have 2 identicle tyres fitted and inflate them to the exact same pressure then messure the circumference. there will definately be a difference. it wont be much (0-5mm), but they will be different. you answered it yourself when u said:

"the sidewal is designed to flex and distort. its normal for a tyre to do that (within reason) but when you stretch them, youre not allowing much movement. thus the tyre is 'firmer' and doesnt allow it to..... squirm?"

the stretched tyre is under tesion and cant balloon out where as the unstretched tyre will. thus changing the circumference