Re: [ihc] Tire RPM @ 70 mph

["Jim or Ginger Aos" <jaos@xxxxxxxxxxxxxxxxx>]

----- Original Message ----- 
From: "Jim or Ginger Aos" <jaos@domain.elided>
To: "James Lidberg" <jameslidberg@domain.elided>; "Joel M Brodsky"
<jmbrodsky@domain.elided>; <ihc@domain.elided>
Sent: Tuesday, March 16, 2004 8:10 AM
Subject: Re: [ihc] Tire RPM @ 70 mph


> ----- Original Message ----- 
> From: "James Lidberg" <jameslidberg@domain.elided>
> To: "Joel M Brodsky" <jmbrodsky@domain.elided>; <ihc@domain.elided>
> Sent: Monday, March 15, 2004 10:41 PM
> Subject: Re: [ihc] Tire RPM @ 70 mph
>
>
> > Joel,
> >
> > Thanks for your calculation.
> >
> > Is this calculation for the wheel RPM?
> >
> > The little rollers inside the wheel bearings are rotating much faster
> aren't they?
> >
> > Like 10X to 30X wheel RPM?
> >
> > Depending upon their diameter and race's diameter?
>
> The RPM on it outside is the same as the inside.  The difference is the
> surface speed at the circumference.  A 20" diameter tire has to make more
> revolutions to cover 10' than a 30" diameter tire.  But the hub of the
wheel
> turns the same noumer of times as the outside of the tire in a given
> distance. Cheers Jim A.

An additional comment.  If  the RPM is constant, and you have a larger dia.
hub ( bearing race) then due to the increase of circumferance, the bearings
woud have to turn faster than with a smaller dia. hub.  When machining on a
lathe, at the same RPM a 2" dia. shaft has a surface speed twice that of a
1" dia. shaft.  Jim A.
> >
> > - Jim in Mesa
> >
> > > Jim,
> > > just some rough numbers...
> > > 70 mph ~ 103 ft/sec
> > > 31" tire is  pi*D or 8.1 feet in circumference
> > >
> > > 103/8.1 = 12 rev/sec
> > >
> > > or 720 rev/min.
> > >
> > > I think you're okay.
> > >
> > > JoelB
> > >
> > >
> >
> >
> > **************
> > Jim In Mesa - James Lidberg
> > jameslidberg@domain.elided
> > '79 Scout II/4X4/345/Edelbrock 1400/727/D20/3.07
open/PS/PB/4"Trailmaster
> > Copyright 2004 All rights reserved