Q's on 2013 PIU

[Rattlecan]

I'm looking at a 2013 PIU to purchase, but I can't go see it yet. This is a "Chiefs" or "Detective" model with the typical front center console, civilian type but has the shifter on the dashboard and cloth middle row seat.
Does the PIU have the same TMS switch as the civilian Explorers? Where is it on the PIU?

Also, has anyone replaced the 18" stock wheels and tires with something larger? Does the AWD still work normally? I know all four must be the same size, but I'd like to increase the diameter a bit.

thanks,
Rattlecan

 

[Kikinz24]

The piu doesn't have a tms switch I'm currently trying to figure out how to add it if it's even possible. In all reality it just changes the rpms for acceleration it shows more power to rear wheels in snow or sand but I havent tested this to see if it really does. And yes you can change the wheel size as long as the diameter is the same on front and rear.

 

[peterk9]

I'm looking at a 2013 PIU to purchase, but I can't go see it yet. This is a "Chiefs" or "Detective" model with the typical front center console, civilian type but has the shifter on the dashboard and cloth middle row seat.
Does the PIU have the same TMS switch as the civilian Explorers? Where is it on the PIU?

Also, has anyone replaced the 18" stock wheels and tires with something larger? Does the AWD still work normally? I know all four must be the same size, but I'd like to increase the diameter a bit.

thanks,
Rattlecan

Welcome to the Forum.
As Kikinz24 posted, you can increase the wheel size. If you do that, do not exceed 3% of the OEM diameter size. You can use the following site to do you calculations; 245/60-R18 vs 255/50-R20 Tire Comparison - Tire Size Calculator | Tacoma World I don't know what the PIU size is so I just punched in the regular 18" wheel size.
I have OEM 20" wheels and run the Interceptor 18" wheels in the Winter. I actually prefer the 18" wheels. In this case switching a 255/50R20 with a 235/65R18 is an exact match with 0% difference. Good luck.

Peter

 

[kobresia]

It's also possible to alter the overall tire diameter in the vehicle programming. A dealer can do this with IDS via menus, you can do it with Forscan software, a compatible vehicle diagnostic/programming interface, and the list of module modifications (look-up "forscan" on this forum for more detail on the process). There's a spreadsheet with formula to ascertain the correct "known good" settings linked from the Forscan as-built module modification spreadsheet: FORScan 2011-2018 Explorers

What I don't know is how that formula behaves with tire sizes which may be out of its range, or what the max diameter theoretically is.

 

[KayGee]

Not sure why, but I couldn't get the tire size change parameters to save on my 2017 PIU using forscan (726-12-01).

The difference in circumference/diameter between PIU 245/55R18 and retail explorer 245/60R18 is 3.4%.

The difference in circumference/diameter between PIU 245/55R18 and retail explorer 255/55R20 is 5.0%.

If you subscribe to the 3% rule above, then you pretty much can't use any factory wheel/tire combinations from a retail explorer on a PIU...

 

[Kikinz24]

Not sure why, but I couldn't get the tire size change parameters to save on my 2017 PIU using forscan (726-12-01).

The difference in circumference/diameter between PIU 245/55R18 and retail explorer 245/60R18 is 3.4%.

The difference in circumference/diameter between PIU 245/55R18 and retail explorer 255/55R20 is 5.0%.

If you subscribe to the 3% rule above, then you pretty much can't use any factory wheel/tire combinations from a retail explorer on a PIU...

I do believe the 3% rule is applied on the max tire wheel combination of vehicle is offered with so it would be 3% above a 255 50-20.

 

[Rattlecan]

So...what happens if you violate the 3% rule?
Does the Advance Trac stop working or throw an error code?
Your odometer/speedometer become inaccurate?
Does the AWD system stop working correctly?

thanks,
Rattlecan

 

[peterk9]

................Also, has anyone replaced the 18" stock wheels and tires with something larger? Does the AWD still work normally? I know all four must be the same size, but I'd like to increase the diameter a bit.

thanks,
Rattlecan

You can increase the wheel/tire size as long as you don't exceed 3% of the OEM size. You can use this handy site; Tire Size Calculator - Compare Tire Sizes | Tacoma World

Peter

 

[peterk9]

So...what happens if you violate the 3% rule?
Does the Advance Trac stop working or throw an error code?
Your odometer/speedometer become inaccurate?
Does the AWD system stop working correctly?

thanks,
Rattlecan

Yes your odometer would be off unless you have an exact match. It will also put extra strain on brake and suspension components. Also it would affect systems like ABS and possibly Traction Control which are factory programmed to operate on the OEM SIZE. FYI, I have 255/50R20 on my Platinum but run 235/65R18 Winters. The diameter difference is 0%.

Peter