Car Tyres - Change size 185 to 165?

Goodadvice75

Hi,

This may be a very dim question, so pls forgive someone who is clueless with cars. We need new tyres on a VW Polo. The existing ones are "185". But when we go on website to search for tryes by registration number the websites show 165 as being standard for this car.

I don't know how/why the ones we have are 185, but as 165s are cheaper is there anything to stop us changing to 165s? Would we have to change the whole wheel (metal bit) as well if we did this? Clueless.... but hoping to save some pennies if possible.

mikey72

Have you got alloy or steel wheels fitted?

masterlumps

you will not save money as you will then need 4 new tyres as opposed to just one (assuming your spare is ok when you check it)

poppasmurf_bewdley

Ask for advice from the tyre fitting place.

You can fit different size tyres on any car as long as they are the same on each axle, but bear in mind they will probably change your speedo readings. You don't need the same size on all four wheels, ie you can have 185's on the front two wheels and 165's on the rear two (unless 4x4).

thefishdude

has your car got standard whjeels are the rest aof teh details correct many cars come with various size wheels possible depending on what the first buyer specified. for example when i put my detail.s in for my car there are 3 possible option of tyres depending on what alloys are fitted to car.

Trebor16

poppasmurf_bewdley wrote: »

Ask for advice from the tyre fitting place.

You can fit different size tyres on any car as long as they are the same on each axle, but bear in mind they will probably change your speedo readings. You don't need the same size on all four wheels, ie you can have 185's on the front two wheels and 165's on the rear two (unless 4x4).

Changing tyres for a different size won't necessarily change your speedo reading. It depends on the wheel rim diameter and the profile of the tyre chosen rather than the width of the tyre. This calculator will tell you the effect of different size/profile tyres will have on your car.

http://www.miata.net/garage/tirecalc.html

The standard wheel/tyre combo on my car is 205/55R16. I have fitted winter tyres which are 195/65R15. The rim size is 1 inch smaller but the profile of the tyre is higher (65% v 55%). The difference in rolling radius of the two tyres is 2mm, which is so negligible. My speedo reading is not affected.

mikey72

It usually won't if you stick to manufacturers specs.
From the sizes here, I would guess the website has given the size for steel wheels, and the op has alloys, or possibly low profile tyres on the steel wheels.