Correct tire size question

[KRAM36]

Originally Posted by Topless

Negative ghostrider, stock 981 Boxsters typically run 26" diameter in front and 27" diameter in rear. I ride right seat in a LOT of 987/997/981/991 cars at the race track as an instructor. No twitch, no unusual tire wear as long as the alignment was set up for the type of driving they do.

I drove my street 986 for 10 years and 100 track days experimenting with a lot of different tire sizes, no twitch unless I had too much rear sway bar.

Here are stock sizes for a 2013 Boxster. Note the difference F/R in diameter and revs per mi. Different sizes, no twitch.
https://www.tirerack.com/tires/tires.jsp?tireMake=Bridgestone&tireModel=Potenza+RE-71R&frontTire=345WR8RE71R&rearTire=645WR8RE71RXL&vehicleSearch=true&fromCompare1=yes&autoMake=Porsche&autoYear=2013&autoModel=Boxster&autoModClar=


My 2009 Cayman runs 25"F, 26"R as stock sizes.
https://www.tirerack.com/tires/tires.jsp?tireMake=Michelin&tireModel=Pilot+Sport+4S&frontTire=34YR8PS4SXL&rearTire=64YR8PS4SXL&vehicleSearch=true&fromCompare1=yes&autoMake=Porsche&autoYear=2009&autoModel=Cayman&autoModClar=

Here are stock sizes for a 987.2 Carrera. 25"F, 26" R
https://www.tirerack.com/tires/tires.jsp?tireMake=Michelin&tireModel=Pilot+Sport+PS2&frontTire=34YR8SPTPS2XLN4&rearTire=64YR8SPORTPS2XLN4&vehicleSearch=true&fromCompare1=yes&autoMake=Porsche&autoYear=2009&autoModel=911%20Carrera%20Coupe&autoModClar=

I think somebody has been yanking your chain a bit KRAM.

Not negative. Just because a number goes from 26 to 27 does not make it a full 1", nor does your statement that ALL 987, 997, 981, 991 run 1" smaller diameter in front than the rear hold true.

I can tell the difference, you can't, no big deal.

Only person yanking chains is you. My Boxster is my DD and it's my only vehicle, it's been that way since 2014. I notice everything on my car when something changes. I personally do not like faster rotating front tires, it throws off the balance to me.

I'll will always recommend getting your tires to rotate as close as possible to the same speed. Nothing wrong or illogical in my recommendation and you're not going to change that.