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.
i heard from somewhere that when u install fuel management/piggyback to a VVT-i/DVVT engine, we must first diable them... if not, it will be quite hard to tune the fuel....
is that true?? i highly doubt dat la...but...
hi all member here, i need some suggestion for u'll cos i need to upgrade my step to more bhp so what sould i need to do... now i got some choose like changing to a biger turbo; put in 272 cam; or haltech? so which 1...