17s to 18s - Qs

[bantam1]

Have fitted OEM RSTTs to my S3 today in place of the standard 17" Avus wheels. Before fitting I weighed the wheels (couldn't find the info about relative weights) and found the RSTTs to be approx 3 lbs heavier. I wanted to get lower profile tyres on the car to aid handling but was worried about this additional weight doing the opposite.

I am wondering what other peoples experience has been in terms of handling when making this change. First impressions are not that impressive but I have also had 4 new F1s fitted today and I'm sure these will take a while to wear in. I've set the pressures to 34 front and 38 rear (was running 30 front and 34 rear on the 17s which seemed to give good front end bite).

I know I'm being impatient and need to give this a bit of time before making up my mind but I'm interested in other views about the differences before and after.

Couldn't afford good lightweight wheels by the way.

Cheers,

B.

 

[Tallpaul]

Increasing unsprung weight is never a 'good' thing it takes more effort to actually get heavier wheels moving and then getting them to change direction requires more energy too. How noticeable that is on the road will depend on the weight increase - also, if you'd had rubbish tyres on your 17's and put 18's on with good tyres then the improvement in grip from the new tyres may have offset the loss in perfomance from the weight increase so it's swings and roundabouts in a way.

Lower profile tyres will provide less 'shock absorption' through the sidewalls so they will skip around a little more than your old ones. Sensibly you are running lower pressures than before, personnaly i'd be tempted to try 32 psi and see how it felt.

 

[Tallpaul]

Read that totally wrong, you've upped the pressure on your new tyres!

Yeah, personnaly i'd run about 32psi all round but it's worth experimenting with tyre pressure to find out what's best for you. I'd suggest 38psi is too high on the back, if you aren't carrying passengers or a heavy load in the boot then the rear tyres will mostly be making contact at the middle of the tread - halfing the contact between you and the road!

 

[The Slug]

I changed from 17's to 18's and thought they were fairly light compared to Sportec's alloys both are/were running F1's , haven't noticed any more "effort" from pulling away, one thing i did notice, better response on steering and seems to roll (coast) easier than the 17's. Also slightly firmer ride to which i think runs better in the corners too with less flex in sidewalls.

 

[bantam1]

Read that totally wrong, you've upped the pressure on your new tyres!

Yeah, personnaly i'd run about 32psi all round but it's worth experimenting with tyre pressure to find out what's best for you. I'd suggest 38psi is too high on the back, if you aren't carrying passengers or a heavy load in the boot then the rear tyres will mostly be making contact at the middle of the tread - halfing the contact between you and the road!

I was going off the tyre pressures quoted in the FAQ section where 34F/38R seemed to be the combo of choice for handling. Running a front / rear pressure differential really made a difference (positive) on the 17s.

Cheers,

B

 

[silver75]

When went from the 16s to 18s on my A3, 1st thing i noticed were the increased road noise also a slight dip in accelaration and fuel consumption.. but then again I bought my wheels for the looks without knowing the weight so cant complain.