Does Increasing wheel size effect performance?

[Maj3sticCr0w]

Was considering upgrading from 18" to 19 or 20 but what effects does this have on how the car performs? What are the pros/cons of upgrading? Would need to have guards rolled etc to accommodate bigger wheels.

[Ben]

Was considering upgrading from 18" to 19 or 20 but what effects does this have on how the car performs? What are the pros/cons of upgrading? Would need to have guards rolled etc to accommodate bigger wheels.

Yes it does!

Less torque as the rolling radius is bigger, therefore less power to the ground. Wheels will be heavier, so harder for the car to turn = less power to the ground as well. Plus all the other stuff that goes with bigger wheels like lowering, changing the roll centre (maybe) and guard rolling etc. With 20's you'll need low profile tires, so ride will be harsher and won't corner quite as well.

Most guys that track their cars go the other way, down to 17s from 18s (just for the track)

[Dropz]

It effects the accuracy of your speedo, causes the wheel bearings to wear immaturely depending on offset, size etc due to the increased loads. As you know the guards may need rolling to fit, may even need to dial in some camber if they're too wide.

This is what it can do, with the correct size tyres your speedo will be fine, and the difference on the wheel bearings isn't very noticeable. Biggest thing to look out for is what size wheel and width is easy to buy tyres for. if it's an uncommon size tyres will be more expensive.

[dmh87]

Wow never thought about it, but that makes so much sense.

Excuse me for my ignorance but I'm not too sure if this will make a big difference for me would I be disadvantaged much?
I've changed from stock 215/45Z/R17 to 225/40Z/R18

[Dropz]

Nah it should be fine. The tyre fitters will check the rolling diameters of the tyres and give you the most suitable size tyre for you're car.

[Robbks]

bigger wheels do not necessarily change handling
if your tyres and wheels overall are a different circumference then this will affect acceleration/ top speed by effectively changing the gear ratios
but normally when you upsize the rims, you use a lower profile tyre to keep the circumference exactly the same.

Some of the more serious drag racing guys that are using street cars will run different tyres to get optimum resulting gear ratios.

however, if your new wheels and tyres are heavier, then it will effectively cost you power at the wheels and braking effieciency, but you will have some gains from increased intertia aswell.
lighter wheels tyres allow more effective power/ acceleration, but with a reduction in that inertia level.

then any difference in overall tyre/ wheel width and/ or track width of the car can have both benefits or drawbacks as far as handling and grip is concerned