Calculate the stress on the supports of a petrol tank and check for resistance conditions.

The internal dimensions are length $L = 8 \text{ m}$, width $W = 5 \text{ m}$, and height $H = 2 \text{ m}$.

$$V = L \times W \times H = 8 \text{ m} \times 5 \text{ m} \times 2 \text{ m} = 80 \text{ m}^3$$

The density of petrol is $\rho = 8.8 \text{ kg/m}^3$.

$$m_{\text{petrol}} = \rho \times V = 8.8 \text{ kg/m}^3 \times 80 \text{ m}^3 = 704 \text{ kg}$$

Using the acceleration due to gravity $g = 9.81 \text{ m/s}^2$.

$$W_{\text{petrol}} = m_{\text{petrol}} \times g = 704 \text{ kg} \times 9.81 \text{ m/s}^2 = 6906.24 \text{ N}$$

The weight of the tank is $W_{\text{tank}} = 500 \text{ N}$.

$$W_{\text{total}} = W_{\text{tank}} + W_{\text{petrol}} = 500 \text{ N} + 6906.24 \text{ N} = 7406.24 \text{ N}$$

Each support has a diameter $D = 32 \text{ mm} = 0.032 \text{ m}$.
The radius of one support is $R = D/2 = 0.032 \text{ m} / 2 = 0.016 \text{ m}$.
The cross-sectional area of one support is:

$$A_{\text{one support}} = \pi R^2 = \pi (0.016 \text{ m})^2 = \pi \times 0.000256 \text{ m}^2 \approx 0.00080425 \text{ m}^2$$

Since there are four supports, the total cross-sectional area is:

$$A_{\text{total}} = 4 \times A_{\text{one support}} = 4 \times 0.00080425 \text{ m}^2 \approx 0.003217 \text{ m}^2$$

Stress $\sigma$ is defined as force per unit area.

$$\sigma = \frac{W_{\text{total}}}{A_{\text{total}}} = \frac{7406.24 \text{ N}}{0.003217 \text{ m}^2} \approx 2302390 \text{ Pa}$$

Converting to megapascals (MPa):

$$\sigma \approx 2.30 \text{ MPa}$$

The condition of resistance is verified if the calculated stress ($\sigma$) is less than or equal to the allowable stress ($\sigma_{\text{allowable}}$) for the material of the supports.

$$\sigma \le \sigma_{\text{allowable}}$$

Since the problem does not provide an allowable stress value for the support material, we cannot definitively verify the condition of resistance. We have calculated the stress on the supports.

The stress on the supports is approximately $\boxed{\text{2.30 MPa}}$.
To verify the condition of resistance, this calculated stress must be compared to the allowable stress of the support material, which is not provided in the problem statement.