Tire Size

[byron maxwell]

Re: ride heights 215/85 E vs 225/75 E; My Michelin references says their
XPS Rib 215/85 Loaded Radius is 14.3", the 225/75 is 13.7". So the 215s
will raise the rear 0.6".
byron maxwell/chaparral

 

[gene]

I have the 159s 85 also. It is just hard for me to see this little
difference make much difference in the torque to the tires. I have the
3.46 final and I considered doing what you are looking at. Just cannot
think this will change much in my system.

gene

>Re: ride heights 215/85 E vs 225/75 E; My Michelin references says their
>XPS Rib 215/85 Loaded Radius is 14.3", the 225/75 is 13.7". So the 215s
>will raise the rear 0.6".
>byron maxwell/chaparral
>
>
Genef -- 77PB/ore/ca
GMC MOTORHOME INFORMATION
mr.erf
http://www.california.com/~eagle/

 

[john wright]

Be aware that the circumference of the tire set the drive ratio. There
is a 5% change in tire circumference between these 2 tire sizes. That
would change your 3.07 to a 2.92 ratio and your 3.46 to a 3.29 ratio.

J.R. Wright

>
> I have the 159s 85 also. It is just hard for me to see this little
> difference make much difference in the torque to the tires. I have the
> 3.46 final and I considered doing what you are looking at. Just cannot
> think this will change much in my system.
>
> gene
>

> >Re: ride heights 215/85 E vs 225/75 E; My Michelin references says their
> >XPS Rib 215/85 Loaded Radius is 14.3", the 225/75 is 13.7". So the 215s
> >will raise the rear 0.6".
> >byron maxwell/chaparral
> >
> >
> Genef -- 77PB/ore/ca
> GMC MOTORHOME INFORMATION
> mr.erf
> http://www.california.com/~eagle/

 

[gene]

Yep I calculated that also,I also took 5 % of the rpm which is 150 rpm at
3000 rpm which also looks like a small number.
so I guess I am not sure if the 5 % goes through all of the calculations.

gene

>Be aware that the circumference of the tire set the drive ratio. There
>is a 5% change in tire circumference between these 2 tire sizes. That
>would change your 3.07 to a 2.92 ratio and your 3.46 to a 3.29 ratio.
>
>J.R. Wright
>

>>
>> I have the 159s 85 also. It is just hard for me to see this little
>> difference make much difference in the torque to the tires. I have the
>> 3.46 final and I considered doing what you are looking at. Just cannot
>> think this will change much in my system.
>>
>> gene
>>

>> >Re: ride heights 215/85 E vs 225/75 E; My Michelin references says their
>> >XPS Rib 215/85 Loaded Radius is 14.3", the 225/75 is 13.7". So the 215s
>> >will raise the rear 0.6".
>> >byron maxwell/chaparral
>> >
>> >
>> Genef -- 77PB/ore/ca
>> GMC MOTORHOME INFORMATION
>> mr.erf
>> http://www.california.com/~eagle/
>
Genef -- 77PB/ore/ca
GMC MOTORHOME INFORMATION
mr.erf
http://www.california.com/~eagle/

 

[gene]

When I asked Osborn , he said he had put in the 3.42 from Texas

This is all I know

gene

>

>
>3000 rpm which also looks like a small number.
>so I guess I am not sure if the 5 % goes through all of the calculations.
>
>gene
>
>

>>Be aware that the circumference of the tire set the drive ratio. There
>>is a 5% change in tire circumference between these 2 tire sizes. That
>>would change your 3.07 to a 2.92 ratio and your 3.46 to a 3.29 ratio.
>>
>>J.R. Wright
>> >>
>
>Gene -- J.R. Wright is "right". The gear ratio changes directly based on
the
>ratios of the circumference of the tire. Using his data for the radius of
>each tire, one tire would have a circumference of 86..86 inches and the
>other would have a circumference of 90.66 inches. Thus, a 3.07 ratio would
>drop to a 2.94 (86.86/90.66 * 3.07) and a 3.42 would drop to 3.28. This is
>about a 4.2% change. By the way, do you have a 3.46 or a 3.42? I
>understand that the Cinnabar one is 3.42.
>
>Emery Stora
>77 Kingsley
>Santa Fe, NM
>
Genef -- 77PB/ore/ca
GMC MOTORHOME INFORMATION
mr.erf
http://www.california.com/~eagle/