Tyre sizes - which are acceptable?

[slow74kWdiesel]

Now then. I have 205/55 R16 tyres on my A4 100BHP TDi Avant (16" Trapeze rims). I have just acquired (ebay) a set of identical rims with 215/55 R16 tyres on them.

The sticker on the car (the one on the B-pillar, visible when you open the driver's door) lists both the above sizes of tyre. QUESTION IS: Does this mean that I can fit either size of tyre to my car?

I realise that the 215/55 tyres will increase the overall diameter of the wheel relative to the 205/55s and thus ,when fitted to the front wheels, the speedo will read slightly lower for a given speed. I'm not overly concerned about this as, if my GPS unit is to be trusted, the speedo is currently reading approx 4mph too high.

If the 215 tyres are ok, what differences can I expect in the handling of the car after changing over?

[Stupark]

" 215/55 R16"

The sizes of a tyre are always width first. i.e. 215 is the width of the tyre 55 is the aspect of the tyre wall, and the R figure is the size of the rims that the tyre fits.

So to answer your question, seeing as both sets of tyres have 55 aspects and they are both on 16" wheels, there will be no conversions needed to read your true speed, and your speedo should be correct. The 205 tyres are narrower than the 215 tyres, and in theory should give you more grip/contact with the black stuff!! This, however is not always the case, as one of the best cars I've ever had for ploughing through the snow was a 1988 vauxhall nova saloon with tyres more apt for a bicycle!!

Hope this helps

Stu.

[slow74kWdiesel]

Hi Stu and cheers for the reply.

As I understand it, aspect ratio is the height of the sidewall expressed as a percentage of the width. Thus a 205/55 tyre has a sidewall height of 0.55 x 205 = 112.75mm and a 215/55 tyre has a sidewall height of 0.55 x 215 = 118.25mm. I have calculated that this only equates to a 1.73% increase in circumference so it will make no discernable difference to the speedo reading.

I was just wondering if anyone out there was aware of any reason that I should not use the 215 tyres on my car.

I'm going to speak to a local tyre dealer today and I might even phone the local Audi dealer.

[danclyon]

Hi Stu and cheers for the reply.

As I understand it, aspect ratio is the height of the sidewall expressed as a percentage of the width. Thus a 205/55 tyre has a sidewall height of 0.55 x 205 = 112.75mm and a 215/55 tyre has a sidewall height of 0.55 x 215 = 118.25mm. I have calculated that this only equates to a 1.73% increase in circumference so it will make no discernable difference to the speedo reading.

I was just wondering if anyone out there was aware of any reason that I should not use the 215 tyres on my car.

I'm going to speak to a local tyre dealer today and I might even phone the local Audi dealer.

Either should be just fine and the difference in speedo, if there is any, will be consumed in the built-in over-read at >40mph anyway.

Cheers,
Dan.

[ali_a4_avant]

The letter, eg. R, V, W is the speed rating, nothing to do with size.

[sline002]

am using 225-17-45 in belgium the car drive very fine and i think you can even use 235