OK, finally got round to getting some tyres for my octy alloys and spent an hour or so fitting them and cleaning my old ones up. Look fantastic - will post some pics when I get the chance.

However, I have a question:

Now that I have dropped from 45 to 40 tyre profile, do I need to increase the tyre pressure at all to compensate? At the moment, I just have them at the same as the 16"ers. Can anyone help???

Thanks,

Don't think it matters so much. I usually run around 32 in my 205/40s but I'm not aware of any real reasons as to why you may need different pressures in slightly lower profile tyres. Would be nice to know though, if there is.

Anyone else have any thoughts on this?

Increasing tyre pressure doesn't make a difference.

The octi alloys are 17s and you're running 40s on them. The fabia alloys are 16s and you ran 45s on them. They're pretty much the same ride height in the end. The extra inch and the lower width/percentage are in balance.

If you put 45s on the 17s, thats where the difference would have been in ride height (the car obviously having been 'higher').

Every tyre is made to run a certain psi, so increasing tyre pressure doesn't make a difference. You'll just mess up the tyre by putting in too much or having to little air in.

Just out of interest, how much heavier are the Octy 17" alloys?

The Octavia 16" vRS alloys are lighter, I weighed them on a lorry weighing machine before I fit them, nearly 1k a corner, 4 bhp on the unsprung weight

but the tyres will be lighter as smaller sidewalls...? in theory should balance out...

good point

Pictures above!

They do look quite nice... although whenever I have seen Fabia's with those on, somehow they just seem to look too big to me.

I suspect I'll be in the minority about thinking that.

Still

I think they look great. Fill the arches nicely and the car's at a good height. Top modification IMO.

Look superb mate! Can i ask how much it has knocked your speedo out if any???? And whats the dealio with fitting them??? Do you have to change all the tyres on them???

Look superb mate! Can i ask how much it has knocked your speedo out if any???? And whats the dealio with fitting them??? Do you have to change all the tyres on them???

I don't think they will have changed the speedo accuracy much as I have dropped the tyre profile accordingly - therefore the circumference will be similar to before. Fitting was no problem - just go straight on! I did have to buy 5 new 40-profile tyres (4 on the car, and one for the spare alloy), but thankfully I know a man who knows a dog etc. etc.... so I go them a bit cheaper than usual.

Very happy with the look, and the handling is sharper than before. However, you can feel road imperfections very clearly now as the tyres have quite still sidewalls - good for handling, less so for comfort. Haven't had a chance to try out the grip yet as I'm running the tyres in for a few hundred miles. Will wait and see!

Dave, they look great!

Top stuff

Just noticed you have a cheeky after market exhaust on there matey? Whats that???? What make is it?

Just noticed you have a cheeky after market exhaust on there matey? Whats that???? What make is it?

Milltek, do a search lots of stuff on them!

Dave - remove the dealer sticker, letting the rear end down

Very, very nice...

*stores mental note for future reference*

Dave - remove the dealer sticker' date=' letting the rear end down [/quote']

Good point mate... haven't actually thought about it until your mention. Much more noticable when looking at the photo. What's the best way to get them off???

Just noticed you have a cheeky after market exhaust on there matey? Whats that???? What make is it?

I'd forgot to put it in my signature - but I have now. Thanks for the prompt!

Good point mate... haven't actually thought about it until your mention. Much more noticable when looking at the photo. What's the best way to get them off???

I used a hair dryer and warmed it for a minute, then it was so easy to pull off it almost fell off, didnt leave a residue either

A quick spin through the very handy calculator at http://www.chris-longhurst.com/carbibles/index.html?menu.html&tyre_bible.html reveals

205/45/16 Rolling Radius 295.45mm Circumference 1856.37mm

205/40/17 Rolling Radius 297.90mm Circumference 1871.76mm

Difference in circumference - 15.39mm or 0.83%

So when your speedo reads 70mph, you're actually travelling at 70.58mph

Not bad at all - You could have that variation on tyre tread depth

Spot the maths geek!!!

Only kidding...

Spot the maths geek!!!

Only kidding...

Nope - Spot the cut and paste!!

Here are mine with the 16" Octavia vRS Estate alloys on They look much better in the flesh and definately a subtle but noticable difference, also I don't have the handling/new tyre/noise problems that you would notice on the 17" versions. Just needs lowering now

(sorry it's not clean )