Big Wheels Less speed?

[thomasfto]

I did take out another FTO with 18" wheels on it. It was a GR with mad mileage and no NCT. and the performance difference was just ohhhh my god! some much slower. The 0-60 was like a day, They where a cheap make alloy.

Does any know if a set of OZ 17" would be as good as the 15 or 16" standard FTO alloys would they slow the car down at all?

[Myfeckin FTO]

Don't think that a 17 inch wheel (with a 40profile) would be any slower than the standard 16inch wheel (with a 50profile) unless the alloys are significantly heavier than standard - I would imagine that the increase in unsprung weight would have a more detrimental effect on handling than speed.

I think you probably came accross a dog of a GR (bet it was a tip as well).
I had a Tip GR - very clean with 20,000miles on standard 16 inch alloys - but it would not compare with my present GPX manual which runs on 17inch lightweight "work rsz" alloys (215/40 ZR Bridgestones).
My Manual Mivec is a far quicker car - esp since it got a thorough service with the addition of an ITG maxogen filter, denso iridium plugs, 3 belt changes and a belly full of fully synthetic. Also found it runs better on 97 Octane with a 3% further octane increase with octane booster. Would really like to get it rolling roaded to find out what power is at the wheels.

Hence I think that engine condition and spec is far more important especially as FTO's aren't getting any younger - vast majority in Ireland are 95-97spec.

Having said that - I wouldn't personally put 18's on my car - I do think that the ideal is a lightweight 17inch 215/40 with a nice set of tyres - Goodyear F1 Eagle or Perelli P Zero from personal experience.

[steelroe]

When you change to larger wheels you should match the tyres as close as possible to keep the circumference as close as possible to the origonal 16",
That way the speed and acceleration times will not be affected
Use the tyre sizer on here http://www.fto-ireland.com/forum/phpBB2 ... php?t=1055

[kevinod]

While I don't think wheel size would have an effect on actual speed, I've always wondered about bigger wheels and the effect on the speed displayed on the dash/miles or km on the clock.

Bigger wheels - one full turn goes further than a full turn of a smaller wheel=> is the mileage underestimated on the clock 'cos its calibrated for a smaller wheel? Also, would the speed displayed be lower than your actual speed? you guys follow what I'm saying?

I think someone told me before that the speed is taken off the gearbox, not the wheels, but I don't really understand exactly how that works, revs ok but (k)mph?? - any of you petrol heads know how that works?

Kev.

[steelroe]

Check this link and it will tell you exactly how far out you speedo will be
http://www.fto-ireland.com/forum/phpBB2 ... php?t=1055

[kevinod]

ah, good link!

Next question, any way to re-calibrate the speedo or compensate for the different size wheels? Would be a c... to be caught speeding when you thought you were going the right speed!

Kev.

[Dave]

anyone know the stock tyre size of a GS?

[soc]

anyone know the stock tyre size of a GS?

I think they came on 15's but most probably had the GPX 16's as an option - so that would probably be 205x50x16

[Dave]

hmm i think the set my mother has are 195, so that's be 195/15/50 or 55?

[CJ]

anyone know the stock tyre size of a GS?

Don't laugh but its 185/70/14

CJ

[Dave]

no way, and here's me driving on 225/40/18's.....
i suppose it's not bad, only running on a 3.7% difference