Alloy Wheels

[PaulD76]

Hello

Recently I upgraded my stock wheels to 19x8.5 front and 19x9.5 rear. I am very happy with the look which to me, is much better, also the handling seems much better (altho m stocks had pretty bad tyres).

http://images5.fotopic.net/?iid=y7y8tj&out...ize=1&nostamp=1

But i seem to have a noticable lose of power. I expect it to maybe pull away slightly slower but its more than i was expecting. It also feels like the gear change is less smooth. Maybe its just being paranoid. I also knew that 16inch was the optimal size but has anyone else had this problem? Im not overly fussed with pure power as i got an Auto NA but if its a common prob/easy fix id be glad to hear of it.

Thanks

Paul

[Leeky]

Unfortunatly its physics against you.

The Bigger the wheels the higher the theoretical top speed will be, but you sacrifice acceleration.

The smaller the wheels the faster the engine can accelerate them but top speed is not as great.

The only way you can put bigger wheels onto a car and not ruin acceleration is if the bigger alloy wheels are actually lighter than the stock ones.

This way the engine can spin them up at the same rate

[PaulD76]

Do'H

Damm physics for you!! Lol.

I will have to find a way to boost the bhp to compensate.

Thanks ;)

[gordypix]

Loving the wheels

[daktari]

Unfortunately i made the same mistake. Back on 16`s now with lower than necessary profile tyres. Which theoretically will give me better acceleration with a lower top speed. Which in the real world is what you need.

[Leeky]

Well i've decided to change my stock wheels for aftermarkets of exactly the same size but of a much lighter compound.

This gives you many benefits -

1 - Speedo wont be out, change to the rolling radius makes your speedo wrong

2 - Tyres i have on my old wheels will go straight onto the new wheels

3 - Using a lighter alloy means i can increase my acceleration and not reduce my top speed

4 - Shouldn't cost as much to declare to your ins company as they are stock size

5 - Handling will not be upset, bigger wheels affect handling greatly

[mad welshman]

Well i've decided to change my stock wheels for aftermarkets of exactly the same size but of a much lighter compound.

This gives you many benefits -

1 - Speedo wont be out, change to the rolling radius makes your speedo wrong

2 - Tyres i have on my old wheels will go straight onto the new wheels

3 - Using a lighter alloy means i can increase my acceleration and not reduce my top speed

4 - Shouldn't cost as much to declare to your ins company as they are stock size

5 - Handling will not be upset, bigger wheels affect handling greatly

←

answer to ur comments lee.

1, speedo wont change at all with larger wheels because u are using lower profile tyres, thus the o/d should be the same

2 only if they are the same width.

3 got to agree with this one, wish i had lightened alloys

4 will cost the same mate, they wont be stock alloys, therefore u will pay the same for 17" or 19"

5 handling will only see effected by putting 19" or bigger on ur soop

i'll get my coat. hee hee

[Karma Supra]

This is exactly why I donl;t go changing wheels for oversize rims...

Why destroy the drive of a fantastic car???

18s on lo pros with the same rolling radius will improve tha handling ona track, -less tyre wall to flex = sharper turn ins. but ona road the loss in "bouncyness" can make the car more skittish..

My g/fs car feels totally different to drive then mine! same car, same setup, same suspension...

she had a strut brace and 18s.... felt loads better on the billiard smooth motorway... as soon as we got to the rougher country lanes mine felt loads better......

[Jesus]

You won't be down on power... it just requires more energy to turn an 18" rim as the weight distribution is pushed further towards the outside of the rim. Hold a 15kg dumbell close to the body and do a bicep curl... now do it again with the dumbell further away from the body. Pretty much the same principal.

The higher top speed argument shouldn't come into consideration really, because you should be going for a tyre size which offers the same diameter and hence circumference as the stock set up. Therefore neither speedo or odometer will be affected, nor gearing.

Acceleration will be increased slightly with lighter wheels, as will braking which is due to forces of inertia and momentum. You will also get quicker turn in on lighter wheels due to the unsprung weight... but as Karma Supra has said, lower profile on a track will help due to the reduction in tyre wall flex.