Only the 45 series fall within the 3% rule, assuming the former is your OEM tyre size. The 50 series tyre is 4.7% already.
Manufacturers don't recommend more than 3% as it would result in bad FC, incorrect speedo and odo meter reading, stress to the bearing, drive shaft and etc. It could also cause brake failure in high speed stopping, due to insufficient leverage of the rotor against the tire size (it's a different story if you're using dinner plate sized rotors).
Try browsing www.1010tire.com they have this delightful tyre calculator which includes speedometer and percentage variance for multiple tire sizes.
This is SportCompact Racing 1st Stage Rebuild the EVO 4-6 engine.
1.Head Full Cleaning
2.Cutting Valve angle
3.New OEM Valve seal
4.Tomei cams 270deg
5.HKS cam Pulley
6.Pen Type Performance Coil
7.ARP head Stud...
I know this is a MLOC forum but since I am driving an Airtrek Turbo, the heart is similar to E7-GTA. Anyway, hope I can get some advice here as I don't get much reply from the Airtreker forum. Here goes: