My daughter has a Mazda Bongo fitted with steel wheels, on which are Wanli 195-70-R15C tyres.

For about a month, one front tyre has been deflating. It takes about four days to lose half pressure. This morning she found that a rear tyre had deflated, with no obvious cause. The front was recently checked by Kwikfit, who could not find any cause for the deflation, but fitted a new valve "just in case" free of charge.

I have seen that Wanli is a cheap Chinese make, and I suspect that these tyres were fitted to improve the vehicle dealer's profit when the Bongo was sold to my daughter three-years-ago.

Do you have any information on this make, and the deflation problem? I am aware that alloy wheels can seep air, but have not heard of steels leaking.