It depends on alot of factors, but your correct in saying tyre profile is one of the primary factors.
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Poor quality and
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/ or overly stiff springs plus poorly match
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/ valved dampers
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(TBH most aftermarket kits are) will ruin ride quality and suspension performance as much as a change to lower profile tyres.
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17" wheels tend to be heavier than 15
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/ 16" wheels, which again compromised damper performance.
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If you get a set of proper lightweight 17" wheels, and stay sensible with the profiles
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(45 is optimum, 40 is the limit, 35 is just too low IMO) then there's no reason they cannot perform just as well as a 15" wheel
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(given similar overall circumference).
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I do agree 16" wheels are about the optimum for a road use car, as they tend to be available in staggered sizes, are as light as the standard wheels in many cases.
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If you are running
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~300bhp
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/ 300 lb/ft then a wider rear tyre is beneficial for traction in most circumstances, and unfortunately many 16" wheels can only take up to a 245-section tyre
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(from a limited number of manufacturers).
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Depends what you using the car for.
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For me, if I end up with another high power MR2, I'll be trying for a 16" front
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(215/45/16 or 225/45/16) and a 17" rear
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(255/40/17) which I think will provide a good balance between grip, compliance and unsprung weight.
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