Strange diffrences in performance with sizes of wheels

[Welshy_Pete]

I had small 175 65 14 rim tyres on my 306 hdi. They were very small when I bought the car also the tyres were all warn out. Anyhow I tested the car out it would wheel spin and pull away really quick an turbo kid in quick ish.

But since Ive put my 185 65 14 alloy wheels on there a big diffrence. The car wont wheel spin or pull very quick and the turbo takes much longer to kick in. Feels as if the power a big diffrence in change.

Does that make such a diffrence?

I changed the fuel filter for a new one as well.

[Foxy-jim]

Are you sure that it's just not in your head?

[Welshy_Pete]

Are you sure that it's just not in your head?

No I put my foot down the car wont wheel spin there no power and turbo kicks in later. Its like it takes alor longer to pick up speed. The old wheels would wheel spin and pull down the road like hell and the turbo kick in faster.

There seems to be a big diffrence in the change Ive noticed. Its not a small change like a k&n panel filter job.

[kingy]

shouldnt be any difference as tou have the same wheel and onlt changed the width.

[Curt]

The rolling radius is so minutely different, so no that won't effect how the car pulls... Obviously the larger the wheel, the more it can effect acceleration...

What you're most likely noticing is a change in grip. You have more now, so they're less likely to lose traction. Shouldn't really be the measure of how your car goes though...

But the wheels cannot make the turbo spool later.

[Welshy_Pete]

The rolling radius is so minutely different, so no that won't effect how the car pulls... Obviously the larger the wheel, the more it can effect acceleration...

What you're most likely noticing is a change in grip. You have more now, so they're less likely to lose traction. Shouldn't really be the measure of how your car goes though...

But the wheels cannot make the turbo spool later.

The new alloy wheels have brand new tyres on.

The old rims the tyres were all warn.

I check the tyre pressures on the new tyres. It does grip more for sure Ive noticed that also the car quiter on road as well.

[Moonstone2.0]

mmm...new tyres are better than worn ones....

[declantg]

Definately because of your tyres IMO, you were spinning up with no grip, now you have grip it should feel faster as it will stick.

[ash240970]

It's because of the rolling radius - look at it like this if you have a tyre completely worn down and totally bald and totally illegal then you have one with 8 mm of tread on it and brand spanking new. The new tyre will do less revolutions to cover the same distance or it will cover a longer distance for the same amount of revolutions because it has a slightly bigger radius, so yes it will in fact be slightly different but not so much as to feel very different - most people wouldn't detect it, incorrectly inflated tyres can also cause a very slight difference as well but that is even less detectable.

[Poodle]

Might find your alloys are heavier than the wheels that were on there, when you've been driving with nice wheels for a while and go back to harriers it suddenly feels like a pig. Also, what brand of filter did you use? Having swapped between a few myself, i'd say it's worth buying genuine, you might find it's restricting fuel flow, which will in turn lean out combustion and delay turbo spool.

[Welshy_Pete]

Might find your alloys are heavier than the wheels that were on there, when you've been driving with nice wheels for a while and go back to harriers it suddenly feels like a pig. Also, what brand of filter did you use? Having swapped between a few myself, i'd say it's worth buying genuine, you might find it's restricting fuel flow, which will in turn lean out combustion and delay turbo spool.

Do the non genuine and genuine fuel filters make much diffrence on the 306 hdi?

[giblets]

Yeh, your wheels are 2-3% larger in terms of rolling radius (more if you include fresh tread etc), which technically will reduce the torque available to you. New tyres will will also have more grip. However, your engine will be runing around 3% slower, so you may get better fuel figures.

[Poodle]

Yes, definitely. Feels sluggish to me with a non-genuine filter, didn't buy it when someone else told me, but try it for yourself.

[Dum-Dum]

Your car feels more sluggish because with the bigger tyres on the rolling radius is increased meaning youve actually geared your car up by 2.5%

[Welshy_Pete]

Also one tyre look alitte low on pressure. So I checked that and it was very low so that didn't help.

Anyway Ive checked all the tyres now there fine. Also the car now pulls much better. I also think the car been parked up alot with having work done to it. So things free up once its moved about like today it pulls fine again now.