Which advantages or disadvantages would I obtain by changing the rim size while keeping the overall diameter of the wheel and the thread width constant?
For example, in http://www.tyresizecalculator.com/ I input 155/65 R13 and I see I could use a 155/55 R14. Let's ignore the change of 2.4% in circumference, that has easily foreseeable effects.
The only test I found is the one by Car and Driver where they used the same car and changed the rim size from 15" to 19".
They noticed worse fuel economy, worse 0-60 acceleration, better max side acceleration with bigger tyres. However, the thread width is not constant, the went from 195 mm to 235 mm.
This would explain at least the max side acceleration and probably the worse fuel consumption. I guess the 0-60 acceleration depends on the overall weight.
My ideas right now with bigger rims:
- worse shock absorption (the rubber is thinner and softer than metal)
- greater risk of damage to the rim with potholes (clearly not with 155/65 R13, but it happens with those ultra thin, almost "spray-on" tyres)
- better handling in corners due to lower deformation of the tyre
- more sudden loss of control: thick tyres deform and then loose grip, the thinner ones sharply go from grip to skid
Anything else? What about when the car is stressed, like in track days? and emergency braking/steering in everyday driving? and so on.