Wheels question

The Edge · 29 Nov 2008 at 07:59

In the not too distant future i'm going to need a pair of tyres on the volvo. Since tyres are £90 for the pair and you can get a decent set of V70 or 850alloys for £100 with good tyres it's would seem to be the route to go down, especially sonce i can put the steels back on when i sell the car.

The problem is that my wheels are 15in and 16in T5 alloys are much more common. My current tyres are 195x60 and the 16in wheels seem to be about 205x50.

Would this **** up my speedo?

Thanks

4T5 · 29 Nov 2008 at 08:34

The Edge · 29 Nov 2008 at 08:44

that's ashame i thought the differance in tyre profile might offset the rim diameter.

4T5 · 29 Nov 2008 at 09:03

Blimey

I'm not clever enough to work that out we need to call in one of the Clever members

The Edge · 29 Nov 2008 at 09:21

malc30 said:
Blimey
I'm not clever enough to work that out we need to call in one of the Clever members

Neither am I hence why i asked the question

The issue as I understand it is rolling radius. So if you increase the size of the rim, you must decrease the profile of the tyre.

The issue here is will a 205x50 tyre on a 16in rim make the required change from a 195x60 R15?

To be honest my speedo reads quite high anyway.

Demon · 29 Nov 2008 at 09:38

I think the 16" setup will over-read by 2.1% compared to the 15% according to my maths..

Or there is this site, which blows my maths out the water..

http://www.club80-90syncro.co.uk/Syncro_website/TechnicalPages/TRC calculator.htm

or this one..

http://www.1010tires.com/TireSizeCalculator.asp

Basically, they are damn close, your speed will fractionally under read..

The Edge · 29 Nov 2008 at 09:50

Given that it currently read 5mph over at 70 it looks like i can proceed.

Thanks