Larger Diameter Tires than OEM - Issues with vehicle / warranty / etc.

[risurfstyle]

I'm looking to increase the tire diameter on my SR5 2025 - my goal is to have a more rugged aesthetic and slightly taller tire diameter.

When I spoke to Toyota parts dept. they said they can do it but it will impact speedometer and possible other issues, but should be OK. Is there anything else I should be worried about? This seems like a very small adjustment, but turns out it's not as simple as I thought to just change the tire diameter. Or am I overthinking it?

From my research I am interested in going from the 30.5" diameter OEM tires to around 31.6". When I use www.tiresize.com and compare here are the results, which gives a pretty significant speedometer error. Who has experience with this to put my mind at ease about taking this step with a new vehicle?

 

[Rellims]

I don't see it being an issue and Toyota is telling you "other issue" just to protect themselves. The factory diameter for off road trim is 32.6 so fit won't be an issue. I think the speedometer tool is likely a good estimate, i'd imagine it changes vehicle to vehicle though. Plus most jurisdictions aren't ticketing for going 3 MPH over. Thursday I hope to be taking mine up to 33.2 and not giving it a second thought.

 

[risurfstyle]

I don't see it being an issue and Toyota is telling you "other issue" just to protect themselves. The factory diameter for off road trim is 32.6 so fit won't be an issue. I think the speedometer tool is likely a good estimate, i'd imagine it changes vehicle to vehicle though. Plus most jurisdictions aren't ticketing for going 3 MPH over. Thursday I hope to be taking mine up to 33.2 and not giving it a second thought.

Thanks, yeah I've never plus sized my tires, so wasn't aware of the downstream issues it can cause. I think it's fine since not going too big. Are you concerned about suspension or other components by going to 33.2"?

 

[mars001]

I wonder if the tire size can be changed with OBD to update the ECU so that it won't affect other things downstream like ABS, cruise, engine performance etc... as they all based on speedometer that will no longer be accurate?

 

[Nodak]

the biggest issue you may encounter is offset from oem specs for the wheel itself. tire size doesnt really affect much except speed indicator offsets.

wheel offsets affects long term the loads you may put on the hub or axle since they are not in line with the oem specs or what the engineers envisioned.

here is a good example of an offset wheel pushing the center of the load further out than oem specs

 

[risurfstyle]

Thanks for this info! If I don't see any offset listed in the specs, I assume it's zero?

 

[Nodak]

most aftermarket wheels are not close to oem specs for offset so they will stick out by varying degress.

i think the 4R oem spec are +58 but most aftermarket are around +25 or +18 which means they will stick out the tires 1-2 inches

 

[richiecass]

I asked my dealer service dept today and I was told the speedometer will self correct by the computer. Many different trim options have different size tires.

 

[ncrunner]

I asked my dealer service dept today and I was told the speedometer will self correct by the computer. Many different trim options have different size tires.

That's interesting. How does it achieve that?

 

[mars001]

I asked my dealer service dept today and I was told the speedometer will self correct by the computer. Many different trim options have different size tires.

I doubt it. That's loads of BS from the service dept. The computer has no way to know, unless it can "read" the tire size marking on the sidewall.

Different trims have different tire sizes and they work because the tire size were preprogrammed at the factory and stored in the flash memory of the ECU.

And may be it could, if the software can match the engine rpm with known tire rotations at the factory and was programmed to self-adjust in a close loop control...

 

[Rellims]

I doubt it. That's loads of BS from the service dept. The computer has no way to know, unless it can "read" the tire size marking on the sidewall.

Different trims have different tire sizes and they work because the tire size were preprogrammed at the factory and stored in the flash memory of the ECU.

And may be it could, if the software can match the engine rpm with known tire rotations at the factory and was programmed to self-adjust in a close loop control...

Maybe they use the onboard GPS to calibrate?

 

[mars001]

Maybe they use the onboard GPS to calibrate?

I guess we'll wait until those who put in bigger tires to see if the speedometer self adjusts. If it does, it should be instantaneous. There should be no learning needed.

 

[richiecass]

ill keep you posted. i am hoping to get mine in a week or so.