Quote:
Originally Posted by F8L
I was hoping someone here could help me with a tire size question.......
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First is that the RPM (rev/mile) values are from a standard condition - some load and inflation pressure. If you are using a different load or inflation pressure, then you would get slightly different RPM's. That's the way indirect TPMS's work to determine a low pressure.
Will the RPM's be the same for different tire sizes? Probably not.
So what Tele man said is true. - and I would add that this likely varies a bit from manufacturer to manufacturer.
I also note that the 2 195/65R15's are both T speed rated, while the 205/50R17 is V rated. That probably means the T rated tires do not have cap plies (circumferetial nylon overlays), while the V rated tire would probably have 2. Cap plies restrict the growth of the tire - and 2 would restrict it even more. If you are using elevated inflation pressures, it is likely that the T rated tires have a larger diameter. In other words, they are bulging out due to the increased pressure, while the V rated tire isn't (much).