1958 owners upgrading from 245/70 to 265/70/18s

[SimplyAnAdventure]

Ok, ran my Garmin inreach on my way into and home from work.

I will say at 30, 40, 50, 60, and 65 the numbers were within 1/2 mph much much closer than I expected to see.

For reference I usually run the GPS permanently mounted on the dash of my Tremor because with the 37’s the speedo is off quite a bit.

As mentioned in my previous post I will have my 275/70R18’s on next week and repeat the test.

I can say with certainty that at least my 2027 1958 speedometer is very accurate with the tiny little stock tires.

 

[Gasherbrum]

Ok, ran my Garmin inreach on my way into and home from work.

I will say at 30, 40, 50, 60, and 65 the numbers were within 1/2 mph much much closer than I expected to see.

For reference I usually run the GPS permanently mounted on the dash of my Tremor because with the 37’s the speedo is off quite a bit.

As mentioned in my previous post I will have my 275/70R18’s on next week and repeat the test.

I can say with certainty that at least my 2027 1958 speedometer is very accurate with the tiny little stock tires.

My experience as well … my 1958 odometer was spot on running the stock 245 tires but is now about 3% off when I switched to the larger 265’s … which not surprisingly have a diameter about 3% higher. Not a big deal, but In hindsight I wished I went up to 275’s like you’re doing.

 

[RideWithYanu]

My only anecdotal experience to add is that on my 285/70s, my speed indicated on either my iPhone GPS location or a Garmin InReach Mini is generally 1 mph higher than my dashboard speedometer indicates.

 

[Dusty1]

My only anecdotal experience to add is that on my 285/70s, my speed indicated on either my iPhone GPS location or a Garmin InReach Mini is generally 1 mph higher than my dashboard speedometer indicates.

Mine as well with my 275/70/18’s.

 

[RideWithYanu]

Mine as well with my 275/70/18’s.

Both our experiences support DubDub’s math, as best I understand it, considering that the Speedo rounds to the nearest whole MPH and the variances between our tires and his would be less than 1mph difference.

 

[DubDub]

Both our experiences support DubDub’s math, as best I understand it, considering that the Speedo rounds to the nearest whole MPH and the variances between our tires and his would be less than 1mph difference.

Yeah, especially w/ Dusty’s being a 1958 originally on 245/70s. it’s either unit or MY dependent (less likely), a good case of confirmation bias (likely), or denialism (most likely). I could maybe accept that Toyota decided to calibrate 31.5” diameter into a MY after my 2025 and going forward… maybe. I’m certainly not going to argue down someone’s justification or analysis for no gain. Choose your own adventure I say! I do very much trust my Garmin eTrex and GPSMAP 65i. Until someone can show me counter data from an equal or higher fidelity device, I’ll continue trying to help those over-reporting with my concrete proof.