Why do the Tires blow on a crane truck when it has electrical contact with overhead lines?

[Joethemechanic]

It was a truck crane where the cab was on the back of a truck skid

There are a lot of small truck cranes that have plenty of boom to get into power lines that only use stablizers and not outriggers and the tires stay on the ground.

You are talking about the small ones on service trucks. To me that doesn't sound what he is describing. It sounds to me like it has an operators cab

 

[OldBroadcastTech]

I thought the rubber tires would act as an insulator.. is it because there is steel inside the tires? I also would think the least resistance path would be the outriggers, which in this instance were directly touching the ground and not on wood blocks. Is there a ground under the hood for battery/ electronic connections? Thinking it could travel there as well.

Tires are typically 30% carbon

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[drcampbell]

I think the conductivity of carbon black in tires is an ancillary benefit, I believe the primary reason it is used is the properties it gives the rubber.

Yes. One of those beneficial & specified properties it gives the rubber is the minimum electrical conductivity necessary for draining away any static charge that might exist on the vehicle body.

Which also allows us to update the advice for what to do after your vehicle is struck by lightning:
- If the tires have not exploded and the engine still runs, just drive away normally.
- If the vehicle has been incapacitated, remain inside the vehicle for a few minutes while the electrical charge drains away, then exit the vehicle normally. No need to leap free and assure that you never contact the vehicle and the Earth simultaneously.

 

[Sberry]

I would have to consciously remember the outriggers actually go out. Wheels on ground and brakes locked stabilize this.

 

[jim dungar]

Yes. One of those beneficial & specified properties it gives the rubber is the minimum electrical conductivity necessary for draining away any static charge that might exist on the vehicle body.

Which also allows us to update the advice for what to do after your vehicle is struck by lightning:
- If the tires have not exploded and the engine still runs, just drive away normally.
- If the vehicle has been incapacitated, remain inside the vehicle for a few minutes while the electrical charge drains away, then exit the vehicle normally. No need to leap free and assure that you never contact the vehicle and the Earth simultaneously.

Do not leave the vehicle normally.
Just because the local charge drains away, you will still be subject to a step differential.