Hey guys, wanna ask a question. I'm currently using 15" stock rims. If I wanna change my rims for better FC, should I go for 15" aftermarket rims or 16" aftermarket rims?
If you're changing rims for FC reasons, rim weight and tyre size/rolling resistance are the key factors to consider. Think about it in 2 scenarios:
Scenario 1:
If you switch from a stock rim that weighs e.g. 7.5kg (which is, btw, the weight of stock Toyota 15" rims from BM), to an aftermarket rim of the same size but weighs 5kg - assuming you use back the exact same tyres, will your FC improve? You can bet that it will.
Scenario 2:
The Honda Jazz stock tyres profile is 185/55/R16. This is an uncommon profile, and for the owner who doesn't want to change rims, the next recommended profile that doesn't mess up the Jazz's speedo readings is 205/50/R16. But the 205 is wider, so it has more rolling resistance, and assuming all other factors remain the same and only difference being the tyres, the wider tyre will result in higher FC.
Read
this to understand more about how bigger/wider tyres affect your FC.
Apply the 2 ideas above when deciding whether to upsize. Basically, if you're hoping to improve FC after an upsize, then you have to make sure your new rims are light enough to counter the effect of increased rolling resistance of the bigger/wider tyres for the new rims.