My book says that a 2003 Honda Civic Si came with 195/60R15 88V's inflated to 33 front 30 rear. The placard should be checked to make sure this is correct, because the next bit of info is dependent on this.
This means the maximum load carrying capacity for the tires is 1184 # and 1146#.
215/40R17's ought to have a load index of 83 if it's standard load (which it doesn't sound like it is based on the inflation pressure writen on the sidewall) or 87 if the tire is an Extra Load (XL) Assuming it is an XL, the tire has less load capacity than the original tires - which is not a good thing! But this also means that MORE inflation pressure is needed than the original tires to obtain the same load carrying capacity.
Doing the calculation, the same load capacity is achieved using 42 psi front and 41 psi rear. But the pressure split needs to be maintained, so 44 / 41 would achieve this without sacrificing load capacity.
Rule of thumb! If you don't use the original tire size, you need to recalculate the tire pressure to obtain the same load carrying capacity.
Hope this helps.
