Nixie Tube driver ICs keep dying
This is a common mistake, and almost invariably for this type of fault you are allowing an illegal state on the decoder chip inputs.
There is NOTHING wrong with using 170-180V for your supply but you must ABSOLUTELY ENSURE that there is always one digit in the 'ON' condition. These Nixie tubes were designed in an era when small scale logic (counters) were used. The counter designs typically did not support illegal states, so the issue was moot. With the use of MCU's proliferating today, the issue of programmed states has to be considered. 

The datasheet for the 74141 shows the problem clearly:



DO NOT reduce your supply to 55V + strike voltage as you will have problems turning on your digits. You need to have about 20-50V across your 20k Ohm resistor to allow for. Also be aware that the strike voltage rises when the tube is cold. 

Since you are driving your decoder from a microprocessor the port pins you are using are set to inputs when the MCU first starts up. the inputs to the decoder will therefore be high and ALL digits will be off. During this time you are imposing a severe over-voltage on the driver outputs. Current will flow through the zener diodes and the weakest zener will pop.....then the next....then the next and so on.
The zeners fail short circuit mostly hence the digits all start to come on. 

The easiest solution is to put an output pull-down resistor on your drive pins to the decoder to handle the power up situation. 
You have to program your MCU to never use the illegal states....ie always have one digit enabled, and don't spend time between digits in illegal states.

If you do need digits to be OFF (leading zero suppression) then you need to clamp the anode voltage for that digit.

Update: 
To answer a question posed, you only need to pull down one input on the decoder to ensure that you always have legal states on the input. 
The current requirements for A,B,C,D vary with A being the least current. Since a valid low is &lt;= 0.8V this can be achieved by putting a 470 Ohm resister from A to ground. If the port pin is set to an input then A=0 so digit '0' will be on. 
When the MCU is driving correctly it will have to source 11mA which is well withing rating. 
You still need to ensure that when program your port pins and they are set to outputs that you handle the values to ensure you don't get an illegal state.