285/70/r17 recalibration?

[Taco4g]

I am looking at getting a new set of tires/wheels. I'm seeing that the most popular fitting here are 285/70/r17's, I'm looking to pair them up with some Method 305's. My question is, how does the speedometer read after putting on these bigger tires and are you guys getting them recalibrated? I'm thinking of getting Mickey Thompson Baja Boss LT 285/70/r17 (Load E).

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[WKTJR1]

This is something I've been wondering myself. If at all possible you would probably have to take it to the dealer.

 

[PullinDoubles]

I am looking at getting a new set of tires/wheels. I'm seeing that the most popular fitting here are 285/70/r17's, I'm looking to pair them up with some Method 305's. My question is, how does the speedometer read after putting on these bigger tires and are you guys getting them recalibrated? I'm thinking of getting Mickey Thompson Baja Boss LT 285/70/r17 (Load E).

Tires I put on are 33.2 inch. GPS on my Radar detector says 2 mph difference. Like 68 and I'm really doing 70. Haven't been able to find out anything. Got to call the dealer or an off road shop.

 

[WKTJR1]

In some earlier threads, someone commented that "it's in the owner's manual." No, it isn't. Since these trucks use various tire sizes, it's clear that different calibrations are required. However, the question remains: can a new size be entered into the ECU (or whatever system controls it)? Considering everything is VIN-controlled, will it even allow you to change the tire size if it's not the original size?

 

[kailua808]

I am looking at getting a new set of tires/wheels. I'm seeing that the most popular fitting here are 285/70/r17's, I'm looking to pair them up with some Method 305's. My question is, how does the speedometer read after putting on these bigger tires and are you guys getting them recalibrated? I'm thinking of getting Mickey Thompson Baja Boss LT 285/70/r17 (Load E).

Assuming you are currently running 265/70/17 the move to 285/70/17 will increase the diameter by 3.5%. So if the speedometer reads 60mph you are actually going 62.1mph. I have the same on a 2021 TRD Off Road with 2.5” Ironman Lift. Looks great. If you can fit 285/75/17 that will give you an extra 1”. Stick with Load C unless you are hauling very heavy loads. Load E is too stiff for this light truck and results in a bumpy ride. Load C will be much more comfortable.

 

[Johno]

I switched from 265/65r18 to 275/70r18 and my speedometer is 3 mph slower at 60 mph. I would like to know if you can get it recalibrated.

 

[dknelson]

This entire issue is strange to me. I installed 285 70r 17’s on my ‘24 off road. I didn’t check the speedometer accurately before the swap. My speedometer now reads 1 mph faster at 55 mph than I’m actually going. 2 mph at 65 to 70. Meaning if my speedometer reads 65 mph, my actual speed is 63 mph. That is opposite of what I expected. I recommend that you check your speedometer before the change. I can only assume that mine was reading about 4 mph slow before installing the new tires so they actually got it closer to correct than the stock tires.

 

[tacorancher]

I switched from 265/65r18 to 275/70r18 and my speedometer is 3 mph slower at 60 mph. I would like to know if you can get it recalibrated.

I switched from 265/70/18 to 275/70/18 and the speedometer still reads 1-2 MPH faster than the speed I’m going. Weird. And my new tires are 0.75” taller after I took inflated and mounted measurements.

 

[Muckle]

My speedometer on 285/70/17s is about 2-3mph slower than actual speed, which tells me my speedometer was wildly off for the stock wheels (265/70/17s). Following to figure out if this can be changed.

 

[Lets taco bout it]

My speedometer also reads 1-2 mph faster than google maps at 65-75 after switching to 285 75 r17s. I did check it before but I don’t remember if it was above or below, I just remember it was 1-2 mph off before too.

 

[Daveintb]

I upgraded to 33” on my Limited, drove to the dealer and was wanting to re calibrate the speedo, after 10-15 min of the service advisor checking with other people he came back and told me that they have no way of doing that. He apologized and I drove away a little frustrated. I guess in the big picture it’s not a big deal.

 

[WKTJR1]

Probably because of this:

Prohibition of Odometer Tampering:

• Under 49 U.S. Code § 32703, it is illegal to:
  • Install or use any device that causes an odometer to register a mileage different from the actual miles driven.
  • Disconnect, reset, or alter an odometer with the intent to change the mileage reading.
  • Operate a vehicle knowing the odometer is disconnected or nonfunctional, with intent to defraud.
  • Conspire to commit any of the above actions.

Service, Repair, and Replacement of Odometers:

• Per 49 U.S. Code § 32704:
  • If an odometer is serviced, repaired, or replaced, it must reflect the same mileage as before the work.
  • If it's impossible to set the same mileage, the odometer should be reset to zero, and a written notice must be attached to the vehicle's left door frame specifying the previous mileage and the date of service.
  • Removing or altering this notice with intent to defraud is prohibited.

 

[Daveintb]

Probably because of this:

Prohibition of Odometer Tampering:

• Under 49 U.S. Code § 32703, it is illegal to:
  • Install or use any device that causes an odometer to register a mileage different from the actual miles driven.
  • Disconnect, reset, or alter an odometer with the intent to change the mileage reading.
  • Operate a vehicle knowing the odometer is disconnected or nonfunctional, with intent to defraud.
  • Conspire to commit any of the above actions.

Service, Repair, and Replacement of Odometers:

• Per 49 U.S. Code § 32704:
  • If an odometer is serviced, repaired, or replaced, it must reflect the same mileage as before the work.
  • If it's impossible to set the same mileage, the odometer should be reset to zero, and a written notice must be attached to the vehicle's left door frame specifying the previous mileage and the date of service.
  • Removing or altering this notice with intent to defraud is prohibited.

Not sure about that. He told me if it was Ford,GM or Dodge it would be no problem. I work in a tractor/trailer shop and we have the ability to re calibrate our speedometers.

 

[tacorancher]

Probably because of this:

Prohibition of Odometer Tampering:

• Under 49 U.S. Code § 32703, it is illegal to:
  • Install or use any device that causes an odometer to register a mileage different from the actual miles driven.
  • Disconnect, reset, or alter an odometer with the intent to change the mileage reading.
  • Operate a vehicle knowing the odometer is disconnected or nonfunctional, with intent to defraud.
  • Conspire to commit any of the above actions.

Service, Repair, and Replacement of Odometers:

• Per 49 U.S. Code § 32704:
  • If an odometer is serviced, repaired, or replaced, it must reflect the same mileage as before the work.
  • If it's impossible to set the same mileage, the odometer should be reset to zero, and a written notice must be attached to the vehicle's left door frame specifying the previous mileage and the date of service.
  • Removing or altering this notice with intent to defraud is prohibited.

I’m a lawyer and actually thought about this, but I don’t think most authorities have ever even considered this. It’s an interesting point.

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