importance of keeping recommended tire sizes?
Warped brake disc, Bad grounds or switch contac problems.
Check to see if the pistons are pushing the pad evenly. You might want to try putting a little grease on the back side of the pad.
On your car I would say high but not complete brake failure. 15 rims would be something like a civic or corolla which don't have great braking systems to begin with. Add additional weight (even with those wheels) and your braking distances will increase and your acceleration will decrease. Brake failure? Not really.but excessive brake WEARabsolutely. But to answer your question 40 is really skinny to use and if your rims aren't well constructed this height might result in dented rims. I definitely suggest running a bigger size as long as they don't rub.it'll throw your speedometer off and be harder to brake but will protect your rims better.
When plus or minus sizing a tire you want to keep the overall diameter within +/-3% of the diameter of the original tire size so as to minimize changes in speedometer/odometer accuracy and gearing. You also need to keep the load carrying capacity to at least what the original tires had (a more complicated discussion) which unfortunately is something those tire size calculators don't take into consideration. For example you probably didn't know that in order to run those 205/40R17's you would have to make sure the tire is in an Extra Load range (tire size should read something like 205/40R17 XL 84H instead of 205/40R17 80H) and you may need to increase inflation pressure by as much as 10 psi to compensate for the tiny air chamber in those low profile tires. You do not risk brake failure by changing tire size.
Changing tire size can often improve the ride and performance of a vehicle through the following methods By selecting a tire of the next lower profile, you can significantly improve the ride quality and handling of your vehicle. Plus sizing has become very popular. In this application, the plus size tire is the same height as the original but its sidewalls are shorter. This change delivers improvement in tire response and handling.
