Changing Alloy wheels - what to consider?

[oneowner2004]

I have found this web-site to be really useful in that it explains in simple terms what has always been a mystery to me, but I must admit that having read all the technical jargon on the web-site, there are still aspects that confuse me:

 

For example, I just purchased a 2004 Suzuki Ignis Sport and the painted white alloy wheels are corroded, so the choice is I either get them refurbished or change them

 

- as it happens I have been offered a set of alloys and this is where I am getting a bit confused, the tyre size is the same, but the wheel rim width and offset is different, and I am having difficulty in working out the effect if any it will have on the car.

 

The original equipment on the car is:

 

15" wheel x 5j offset 45

Tyres are 185 / 55 / 15

 

Proposed New Wheels

15" wheel x 6.5J offset 38

Tyres are 185 / 55 / 15

 

 

Using a calculator I think that the effect would be decrease the internal clearance to the strut housing by 12mm(no problem envisaged), but would add 26mm to the external position of the wheel.

 

- i.e it would fill the wheel arch a bit better as the current wheels do look a bit lost because of the flared wheel arches, plus I have never really liked white alloys.

 

Because of the increased wheel rim width this will increase the track width of the car, but will this type of increase cause any major handling changes or increased wear on the wheel bearings?

 

In addition, as the same size tyres are going on slightly wider rims, will that have any effect on calculating the overall rolling circumference etc - i.e. in my mind the tyres are going to be more stretched widthwise and thus surely it will affect the sidewall height?

 

Or is this type of change within "manufacturers†tolerances and I do not need to worry.

 

Grateful for any comments / advice please.

[Tony]

Hello oneowner 2004

 

The main issue with wheel off-sets is unusability (will it fit?) miss the strut/caliper....

 

Geometrically the problem could be the Scrub-radius... Thread about that here> http://www.wheels-inmotion.co.uk/forum/ind...t=0&start=0 In your case the SR will be moved inboard but the change in the contact patch is very small so i don't feel you would have any problems.

 

If you asked for the worst case scenario the handling would feel light and over reactive, particularly at speed.

 

In my opinion the tyre size should be 195-50/15 for that size wheel.... Good news is the 195mm has a bigger market and are cheaper than the 185mm...... Example i sell the F1 fully fitted for £47

[oneowner2004]

Hi Tony,

 

Thanks for the swift reply

 

- I thought it may affect the scrub radius, but was not confident to work out how etc etc.

 

Interesting comment on the handling, I had noticed that effect on a previous car fitted with wider rims /same size tyres, but did not understand then why it had occurred - I think I do now...........

 

The alloys I am being offered have part used tyres, so once they need replacing I will upgrade to the 195/50's as you suggest - one other benefit of the new size tyre I see is that it should assist in preserving the edge of the alloy better from kerbing, i.e. the 185's will be slightly stretched on the 6.5j rim and the sidewall will be more upright in comparision.

 

Thanks again for your help.

 

Regards

 

Roy

[Tony]

Hi Tony,

 

Thanks for the swift reply

 

- I thought it may affect the scrub radius, but was not confident to work out how etc etc.

 

Interesting comment on the handling, I had noticed that effect on a previous car fitted with wider rims /same size tyres, but did not understand then why it had occurred - I think I do now...........

 

The alloys I am being offered have part used tyres, so once they need replacing I will upgrade to the 195/50's as you suggest - one other benefit of the new size tyre I see is that it should assist in preserving the edge of the alloy better from kerbing, i.e. the 185's will be slightly stretched on the 6.5j rim and the sidewall will be more upright in comparision.

 

Thanks again for your help.

 

Regards

 

Roy

You are very welcome