AndyMc

Hi guys

I've just changed from 16 to 17 inch wheels and my MY98 feels slower.Has anybody else noticed this?Is it due to the extra weight maybe?

old tyres were standard size and new are 215/40/17

Andy

Dave T-S

Assuming the old tyre size was 205/50x16, the rolling diameter is 612mm, and the rolling diameter of 215/40x17 is 604mm, so it will actually accelerate slightly quicker (but in reality you won't notice it).

Same goes for weight of wheels - depends what they are, and may be heavier or lighter, but you won't notice.

If someone masked your fuel gauge, and told you to drive with the fuel tank empty, then full, but didn't tell you which was which, you wouldn't be able to tell - and the weight difference from a full tank to empty would be about 100lbs.

hades

Dave - If someone asked you to drive with your fuel tank empty, you'd definitely notice. no fuel = engine doesn't run = slow car!

Seriously, the difference would be subtle, certainly less than eg the difference between cold damp day and hot dry day. You might notice it, I'm sure you can convince yourself it is different, but in real terms difference would be a couple of percent i.e. insignificant.

Pavlo

The rolling radius on lower profile tyres tends to be close to the static (unloaded) radius that on a higher profile tyre.

So the difference will not be as much as the basic calculation suggests.

I think on one of the Tyre manfacturers sites, possible Toyo, they give actual rolling radius for tyres.

Paul