In the present study, the mathematical prediction with the Paul-Mukunda model is carried out for maximum pressure rise with erosive burning in multi-grain solid rocket propellant. For this study, a cluster of 7 tubular solid double-base propellant grains is selected. The erosive burning model has given a fair idea of the maximum pressure rise in rocket motors. The maximum pressure rise due to the erosive burning effect is quite a lot higher than without the erosive burning effect. The erosive burning model helps in studying maximum pressure rise for various configurations of propellant grains. It is found that lowering the outer diameter (OD) of propellant grains is giving low maximum pressure in rocket motor in comparison to increasing the inner diameter (ID) of propellant grains. A(p)/A(t)(port area to throat area) ratio is maintained same for both the cases. Although in both the cases predicted maximum flow velocity of propellant gases is almost same. It shows that keeping the same A(p)/A(t)ratio and erosive burning effect, the maximum pressure is reduced significantly by lowering OD of propellant grains than increasing the ID of the propellant grains in rocket motor. This study will help to reduce the maximum pressure rise in rocket motors for safe working.