Sorry for a late answer. Yes it`s the dilution ratio I go with mostly and sometimes weaker as 1:5-1:7 even when the cars are not that bad. When it`s really badly dirty or I`m about to reapply the base protection. I mix 50/50 with BH Auto-Foam and BH Surfex HD and no water in the foamcannon bottle and max chemical output on the chemical mix setting on the foamcannon. Sometimes I just go with concentrated Surfex HD and max chemical output on the foamcannon this is very thin foam but still very effective on vehicals with a lot of road film build up on them.
You will notice that the Auto-Foam is very great at breaking down the grime on the tires. I usually don`t need to be scrubbing them and just use the PW to clean them with. If you have an extra foam pump pressure spray bottle you can dilute the Auto-Foam in 1:10-1:15 and use that as a tire cleaner and the Tuf Shine Tire Brush and you are ready to dressing them up again

Surfex HD is even better on tires and I have a foamer with 1:10 and use it on both the tire and rim and wheel wells for a very effective deep cleaning. It also aid if you do this once and take your dedicated tire cleaner like Tuf Shine Tire Cleaner or Adam`s Tire and Rubber Cleaner. And I usually only needs to be reapply these 2 times and have white nice foam on the second application. Have old Michelin and Continental tires that`s usually horrible with the browning. But the combo holds down on the amount of the dedicated tire cleaner which is expensive for me here in Sweden. And this is before I apply the Tac System Tire Coat. So foam Auto-Foam on the wheels and wheel wells and you will be impressed with it`s cleaning ability from it even from the foamcannon.
Please share your experience and thoughts about the BH Auto-Foam. So it`s just not me who likes it so much LOL. Use the water pressure from the PW to clean with and you will see satisfieng results. The aid it gives in the cleaning for me I have not seen any other prewash foam come near. The more harsher TFR foams we have here comes near it but feels harsher on the LSPs for me. Always comes back to Auto-Foam though. Ordered my second 5L jug in the order that Surfex HD 5L had been emptied in LOL. So my favorite combo if I don`t had the urge to test different products LOL is prewash foam and PW clean rinsing it off with Auto-Foam and then multible wash mitts and mf wash pads with Carpro Reset car soap. This would be just what I would use if only choices where 1 product of each step to use. But I`m a sucker for testing other products and switch them up LOL