Calibration for bigger tires.

[Steph1]

Guys,

Those of you with 315/70r17 Preferably BFG K02s, that corrected the tire size via Jscan, tazer or flashcsal, what height did you set to get a good speed match with a GPS ???

Searched and get confusing info. Some say with tire on the Jeep, measure from ground to the corner of the tire, some say use a level and measure height, others say use the manufacturer’s advertised height (in my case 34.4).

Thanks.

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[BDinTX]

I have an AEV procal snap. Below is one of their FAQs with answer. I followed their recommendation.

“I bought 35" tall tires, do I really have to measure them or is 35" close enough?

Yes, you really have to measure the tire. The size listed on the side of the tire can be off by as much as an inch in either direction. All manufacturers’ values are different, and there can be variation in the manufacturing process. An actual measurement with weight on the vehicle, rounded to the nearest quarter inch, is required in order to get an accurate input.”

 

[VTL]

a few tires in the market will measure exactly what they say. Best way is for you to measure them and be sure

 

[Steph1]

I have an AEV procal snap. Below is one of their FAQs with answer. I followed their recommendation.

“I bought 35" tall tires, do I really have to measure them or is 35" close enough?

Yes, you really have to measure the tire. The size listed on the side of the tire can be off by as much as an inch in either direction. All manufacturers’ values are different, and there can be variation in the manufacturing process. An actual measurement with weight on the vehicle, rounded to the nearest quarter inch, is required in order to get an accurate input.”

Alright, but how do you perform the ‘’actual measurement’’??? .

 

[MtCamper]

I run 315 KO2s. Measured by goth GPS and roadside radar guns, I'm about 2 mph faster than dash display. I left is as is.

 

[GATORB8]

I never even pull out a tape measure, I just match to GPS.

1. Set to manufacturer height
2. Go for a drive and whip out an app with a GPS speedo (do not connect your phone to carplay, it will use the speed reading from the Jeep).
3. If the GPS is higher than the Speedo, bump it down. If the GPS is lower than the Speedo, bump it up.

 

[dav_webb]

Guys,

Those of you with 315/70r17 Preferably BFG K02s, that corrected the tire size via Jscan, tazer or flashcsal, what height did you set to get a good speed match with a GPS ???

Searched and get confusing info. Some say with tire on the Jeep, measure from ground to the corner of the tire, some say use a level and measure height, others say use the manufacturer’s advertised height (in my case 34.4).

Thanks.

I just did this on 2 JL's, Installed 315/70R17 BFG KO2's, running 33 PSI. I set the Tazer to 34.5, and then checked it with a GPS Speedo App. It was perfect.

 

[Steph1]

I never even pull out a tape measure, I just match to GPS.

1. Set to manufacturer height
2. Go for a drive and whip out an app with a GPS speedo (do not connect your phone to carplay, it will use the speed reading from the Jeep).
3. If the GPS is higher than the Speedo, bump it down. If the GPS is lower than the Speedo, bump it up.

You might be onto something….. I have a Cplay2 air and my phone automatically connects to carplay….. so used to it that I didnt figure it out.
Thanks ?

 

[GATORB8]

You might be onto something….. I have a Cplay2 air and my phone automatically connects to carplay….. so used to it that I didnt figure it out.
Thanks ?

Yeah, it was a puzzler when I figured it out. I put 35s on my Ram with wireless carplay, and it read perfect before I even used the calibrator, lol.

I think it's one of the reasons why Waze glitches out sometimes if I don't kill the app before getting in the truck. It switches from phone GPS to truck GPS antenna and OBD Speedometer.

 

[BDinTX]

Alright, but how do you perform the ‘’actual measurement’’??? .

Oh sorry, ya I measured from the ground to the top of the tire and to be honest... I probably just eyeballed it to the top, didn't use a level. Note, their directions say round to the nearest 1/4" so it was close enough for me. I haven't compared speedo to GPS.

 

[KevinC11]

With the tire on the Jeep and under load, measure from the ground up to centerline of the center of the wheel. That centerline should be the middle of the knock-out center cap. Take that measurement and x2. This will be the most accurate true height of your tire.

KevinC

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