In game name: JerrY
Details:
When you have car armour on 1900 you can refill it back to 2k,but when you want to buy bullet resistant tires, because one or more tires are flat, you cannot buy because its counting as you already have them, and preventing you to buy.
You need to choose 'Repair vehicle engine and body' from the gas station menu to repair bullet proof tires. You can also use car wash at LS to repair them.
One more thing I noticed is when u are having car armour equipped with bullet proof tires, paynspray does not repair car's tires. But when u are having only bullet proof tires with normal vehicle HP, paynspray repairs tires too.
Bullet-resistant tires works differently from vehicle armor, Vehicle armor simply increases your vehicle HP to 2000, but the default HP is still 1000.
Bullet-resistant makes your default tire health 15 instead of 5, get my point?
It does not temporarily set it to 15 hp but the default hp is 5, it makes the tire normal health 15 until your vehicle is destroyed, so if it was shot and tire HP lowered (you can check /tirehealth), just repairing the vehicle (with bodywork, not just the engine) will fix it and restore it to it's normal HP which is 15 if normal bullet-resistant tires and 30 if super bullet-resistant tires, you dont need to buy bullet-resistant tires again as you already have them on your vehicle but they are damaged and need to be repaired.
Not a bug, moving to invalid bug reports.