Danger: Math!

[BigBody79]

What is the tire size (circumference) need to travel from stair tread to stair tread with out hitting the landing. Let say the stairs have a 11" run and a 7.75" rise.

I can see it in my mind but can get it to work out.

No credit given if you don't show your work!

 

[ord.sgt.26NC]

ain't it bed time?

 

[RatLabGuy]

since when are tires measured in circumference?

 

[Lankford]

Approx 6'2"

 

[RatLabGuy]

and btw the answer is a diameter of ~23.5"

 

[MarsFab]

The tire would have to have a radian arc length larger than Tip of stair to tip of stair which is 11"^2 + 7.75"^2 = 13.455. Radian arc length is equal to the radius of the tire. So the tire would have to be a minimum diameter of 26.911" or have a circumference of 84.55".

 

[RatLabGuy]

Radian arc length is equal to the radius of the tire.

It wouldn't have to be the radius, it could cut across a smaller section. See pic.

 

[MarsFab]

Correct. Radian is the length of the radius laid around a section of the circle to form a segment. If that segment were shorter than point A to point B which is 13.455 then the diameter of the tire would also be smaller meaning that it would it would sit on the point of the riser and slightly on the flat of the tread. The way you've drawn it shows the radius larger than point a to point b.


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[mcutler]

You go boooiieeyyy.... beat me to it

sent from a fancy Samsung Note 2 with an illiterate operator. ..

 

[Croatan_Kid]

I'm pretty sure a set of 44s would work just fine

 

[broncosbybart]

FYI, tire size is inversely proportional to the rate of speed approaching said staircase.

 

[MarsFab]

And the amount of air pressure....


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[Hurley]

rolling radius will get you every time.


(34psi)