mixing tyre sizes?

[sc0rpius]

Hi, I need two new front tyres for my VRS and as I am short of money and have a suspicion they might go bold again I'm finding some on ebay.

ATM they are all 205/50/17 I intend to keep the rear ones as they're oright but if I get something like 215 45 17 would that be such a big difference? I know I have to buy all 17 but are the first two digits really significant?

Edited 19 May, 2011 by sc0rpius

[Shroud]

I asked this question before myself and i understand that as the car is 2wd then so long as you keep the same tyre sizes on the same axle it is ok. Also for the sizes you mention the difference in diameter is not that great. You can check here

http://www.alloywheels.com/tyrecalc.asp

Personally i would keep the tyres the same size though as it might look a little odd with front tyres with a different profile than the rears, although once again, the difference between a 215/45 and 205/50 isn't that great.

The slightly wider 215s should give a little more grip, although the bigger the tyre the more drag on the road and hence slightly worse fuel economy.

[Volvomeg]

Ive got a set of audi s3 wheels as spares for when i get my spiders referbed, they have 225 45 17's on and i thought vrs drove alot better with those than the standard 205 50 17's, only problem was s3 wheels are a wider offset and they rub on rear arch's over bumps,

Going to try the 225's on spiders before i get them referbed to see if they rub or not

[Nick P]

I've been running 215s on the front and 225s on the rear for a little while. I am going to put 215s on the back at some point, but the handling has been absolutely fine.

[billy2981]

personally mate you have done the wrong thing there:

1 your speedo will be out by about 2 mph (they are ouot ne way by a couple but your tyre choise has made it worse)

2 Your will add miles on to the car that it has not done.

3 messes up your fuel economy

17" rims with 205 50 tyres on is the best for eco and everything is almost bang on, 18" rims 225 40 my eco went down by 5-6 mpg ish and 17" with 225 45 on its gone back up to around the 40 mark. Now have LCR 18" rims on with 225 40 18 tyres on so we will see what the change is there.

Look here:

http://www.carbibles.com/tyre_bible_pg4.html

just over half way donwn page.

you should either get the 205 50 17 or 225 45 17 as they are near as the same. On my run out with the 18" wheels on it was 40 mile spot on from my door to the carpark in avonmouth and the same trip with 225 45 17 spiders is just under 42 mile. soon adds up mate.

with 215 45 17 tyres I would at a guess look at 43/44 mile a trip pos more.

end of the day tho you can put what you want on there. but things are not accurate then.

billy

that car bibles is ace too for info.

[billy2981]

Ive got a set of audi s3 wheels as spares for when i get my spiders referbed, they have 225 45 17's on and i thought vrs drove alot better with those than the standard 205 50 17's, only problem was s3 wheels are a wider offset and they rub on rear arch's over bumps,

Going to try the 225's on spiders before i get them referbed to see if they rub or not

na mate 225 45 on the spiders dont rub even on a lowered car, unless its decked.

[wayned]

personally mate you have done the wrong thing there:

3 messes up your fuel economy

17" rims with 205 50 tyres on is the best for eco and everything is almost bang on, 18" rims 225 40 my eco went down by 5-6 mpg ish and 17" with 225 45 on its gone back up to around the 40 mark. Now have LCR 18" rims on with 225 40 18 tyres on so we will see what the change is there.

Thanks I was thinking of running 18"s on mine but going to give it a miss now.

[billy2981]

dont get me wrong 18" suit the car nicely, Its also down to tyres, My best eco on 18" rims was with Replicas, heavy ones lol and cheap budget tyres as they are hard, takes a bit more to get roling but when roling seemed to take no more to keep them going and they let you coast in gear longer so you didnt use any fuel. the TS are lighter so dont in effect store the same ammount of kinetic? energy and hence dont keep you roling as far. all adds up.

You get to know these crappy eco things while driving for Tesco as its all on fleetboard which scores you on your driving. Mine is pritty good atm. challenge is to get it to 100% lol, nearly but one area lets me down (not fuel eco)

Just ask Lloyd lol, he had 20" beasties on his lol. the most expensive rubber bands out there I think.

billy

edit

bear in mind tho that with 18" and 225 40 18 tyres you are actually (only very slightly) making the roling radius of the wheels bigger which will mean it brings the speedo back to more accurate(they say 70 but are more like 67) and you do more miles than the car says and for this reason the MPG will go down as you use the same amount of fuel on the run but the speedo says less than on the 17s(205 50)

All small amounts but over time these things all add up.

[sc0rpius]

Guess ill get the same ones then. Got plenty of time anyway..... :(

[AndyBohen]

Going to try the 225's on spiders before i get them referbed to see if they rub or not

Thats what im running on my spiders, alot more grip with the wider rubber.