Alloy size?

[silver9n3]

Hi all,

Being my first car, it's a 1.2 E and came with standard 14" steels with clip ons. I would like to upgrade these to maybe 16" or 17" inch alloys, and I hope that these would fill the arch gap better without the need for coilies or springs.

Anyone have an idea as to which size will fit best?

Thanks!

[TomG]

I dont know where this myth has come from about increasing alloy size makes the car look lower - it doesnt.

If anything it will look more ridiculous on larger wheels and on stilts.

The rolling diameter of the wheel/alloy combo will be the same if on 14's or 17's. Assuming you use the correct size tyres for the car.

[silver9n3]

I dont know where this myth has come from about increasing alloy size makes the car look lower - it doesnt.

If anything it will look more ridiculous on larger wheels and on stilts.

The rolling diameter of the wheel/alloy combo will be the same if on 14's or 17's. Assuming you use the correct size tyres for the car.

Sorry?

I have a big nasty arch gap on 14s.

Picture the car jacked up. Take the 14s off, put the 17s on. It will fill the gap and would look like what 14s lowered would.

I'm not on about ground clearance lowering, just the appearance and arch gap as I said.

[alexperkins]

As Tom says, using the correct alloy/tyre combo, the rolling diameter is still the same, your just having more alloy and less tyre.

The only way to get less gap is to lower the car, or use tyres that arent suited to the car and send the speedo well out (foolish)

[silver9n3]

As Tom says, using the correct alloy/tyre combo, the rolling diameter is still the same, your just having more alloy and less tyre.

The only way to get less gap is to lower the car, or use tyres that arent suited to the car and send the speedo well out (foolish)

Wait a minute, now I'm not 100% certain on this but bare with me...

Visualise the jacked up car with 14" alloys.

Big arch gap.

Take the 14s off and put some 17s on.

Surely the arch gap will appear smaller?

[alexperkins]

The arch gap is still the same size - its the visual perception that throws you as larger alloy = less tyre

This picture shows it well:



As you can see, the arch gap remains the same. The tyres just get smaller.

[silver9n3]

The arch gap is still the same size - its the visual perception that throws you as larger alloy = less tyre

This picture shows it well:



As you can see, the arch gap remains the same. The tyres just get smaller.

Well this has confused me haha...

I still don't get it as what you attach the wheel to doesn't move.

If you take off a wheel which had 3" of space between the top of the tyre and the arch, and you put on a 2" bigger alloy, how does this not decrease the gap to 1"?

As the suspension doesn't move I really don't get this...

But as a rule of thumb, some 16s would look better on my polo than 14s right?

[alexperkins]

Right, so say you have a 15 inch alloy, and this has a 2 inch tyre wall. and a 3 inch gap

For the purpose of this, we swap it to a 17 inch alloy, but we cant have a 2 inch tyre wall, as then the rolling radius between the old wheel and the new wheel will be massively different, and the cars speedo will be completely off the scale

Therefore, we have to now use a 1 inch tyre with the 17 inch alloy, to make both wheels the same size in overall width, and youll still have a 3 inch gap as the wheels are the same overall size. You just see more alloy and less tyre.

Does that make sense?

In any case, 16" inch alloys, would look much better, but the gap will always be the same until you lower the suspension.

[silver9n3]

Right, so say you have a 15 inch alloy, and this has a 2 inch tyre wall. and a 3 inch gap

For the purpose of this, we swap it to a 17 inch alloy, but we cant have a 2 inch tyre wall, as then the rolling radius between the old wheel and the new wheel will be massively different, and the cars speedo will be completely off the scale

Therefore, we have to now use a 1 inch tyre with the 17 inch alloy, to make both wheels the same size in overall width, and youll still have a 3 inch gap as the wheels are the same overall size. You just see more alloy and less tyre.

Does that make sense?

In any case, 16" inch alloys, would look much better, but the gap will always be the same until you lower the suspension.

Ah I get you!

Thanks for that, but couldn't I get 17 inch alloys with a 2 inch tyre wall then get the speedo calibrated as this would give the perception of a smaller arch gap?

Thanks again.

[alexperkins]

The speedo cant be calibrated that much

Also in doing that, you put more strain on the CV joints, and youll also lose economy as the engine will be working harder to produce the same result

Check out the tyre calculator here to help you choose:

http://www.willtheyfit.com/

As a rough guide to explain it

A 195/45/15 is equivalent to a 195/40/16 which would be roughly equivalent to a 195/35/17

Middle number being the depth of the tyre wall - you can see each size, the wall is getting smaller.

[silver9n3]

The speedo cant be calibrated that much

Also in doing that, you put more strain on the CV joints, and youll also lose economy as the engine will be working harder to produce the same result

Check out the tyre calculator here to help you choose:

http://www.willtheyfit.com/

As a rough guide to explain it

A 195/45/15 is equivalent to a 195/40/16 which would be roughly equivalent to a 195/35/17

Middle number being the depth of the tyre wall - you can see each size, the wall is getting smaller.

Ah I get you, will have a play on that site.

Thanks man!

[alexperkins]

You're welcome