Bigger tire effects on speedo and other systems?

Hey Guys - Quick question relating to a 2016. I'm considering moving to slightly larger tires then my Taco came with. I don't care about actual functional changes such as reduced gas mileage, road noise, vibration, etc.

What I am concerned with is electronic system effects. I know moving to larger tires will affect my speedo and (to a small degree RPM). My specific concerns are with other systems (e.g. gas mileage estimates, etc). These systems (I'm guessing) perform all their calculations based on OE tire size as a primarily parameter. If correct, these systems will be affected.

Is there a simply way to tell the ECU to use GPS data (in combination with other existing sensors) to reprogram the systems so they recognize larger tires?

I know with my other rigs I can reflash ECU's, add inline speedo boxes that alter the signal, etc. I'd prefer to avoid these options as this is a simple work truck and (for now), I'm trying to keep it as stock as possible.

Thanks in advance for any assistance .

 

i have the Bilstien 6112/5160 set at 5/6 and dakar leaf pack on 275/70r17s. i also did the carrier bearing drop. have very slight vibration around 20-35mph. Just need to install 3degree shims in the rear to correct driveline angle. for my speedo i bought the Hypertech Speedo Calibrator, it was 190$ on Amazon. all you do is input your stock tire size in inches or Metric size then input your new tire size in the program. Install took 20 minutes. and my speedo is spot on now. my gas mileage may be slightly less then stock but not much at all maybe .5mpg less And hardly noticeable power loss. I think the truck shifts better with the bigger tires. No regrets.

 

I bet you will be if things don't go well.

Depending on your size change, you may find that your speedo is actually corrected. Many folks do, as most are reading low from the factory. Have you GPS verified what you have now?

And if your speedo is accurate, the ancillary systems will be as well.

 

I’ve read that a a few times also but my speedo was off about 3-4mph at 70. and it was reading horrible gas mileage as it is affected by the speedo being off. . The Hypertech Calibrator is the way to go. I verified correctness with my navigation on my headunit(aftermarket) and on all 3 nav apps on my Iphone (waze, apple maps, google maps)

i say for 190$ it’s worth it as everything will read correctly and your odometer mileage will be true

 

I fully understand your concerns and have said the same to others . In my case I've been modifying jeeps (TJ's XJ's, WJ's) for over 20 years running fairly aggressive (e.g. Mickey Thompson Baja Claws Bias) mud tires on every build up to 37's. I haven't run a standard street tire on any vehicle since 1996 (excluding this work truck).

You're also correct my speedo is already off a bit (2 MPH at 70) based on GPS.

 

Thanks everyone for the feedback on Hypertech Calibrator, etc. I already run a secondary GPS, so I'll always know true speed using that. I'm really more interested in what affect this change would have on all the other systems, which I don't have a secondary option with?

My instincts are telling me to run the exact OE it came with, which was 265-65-17 to avoid possible side effects.

Thanks again

 

You can use Waze gps on your smartphone to tell how fast your going

 

285s look great as well as 265/70/17s. I run that size, my speedo is dead perfect, no power loss nor was the gas mileage was affected. I run a SL rated tire Toyo Open Country AT2 and the weight of the tire and my 4runner pro wheels the weight was the same as my factory sport set up. I'm perfectly happy with the 265/70s because nothing changed, no cutting, shaping fender liners, just no issues what so ever.

 

I've been looking at 265/70/17's as they seem to offer more tire options. I'm guessing it's a more size.

 

I went with 265/70r17's for that reason. There are tire size calculators that can tell you the difference.

Reading 20mph 30mph 40mph 50mph 60mph 70mph 80mph 90mph
Actual 20.7 31 41.3 51.6 62 72.3 82.6 92.9