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Re: P Zero 205 45 16's...
[Re: X19_pilot]
#1231131
26/06/2011 11:16
26/06/2011 11:16
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Joined: Feb 2006
Posts: 5,390 Essex
Trappy
Forum is my life
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Forum is my life
Joined: Feb 2006
Posts: 5,390
Essex
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How much will the speedo be thrown out?
Assumption Indicated Speed (mph): 60 Standard speedo inaccuracy: 5.00% Standard tyre size Width (mm): 205 Profile (%): 50 Size (inches): 16 Sidewall (mm): 102.5 Actual speed at indicated 60mph: 57.0 Rolling circumference (inches): 75.6 Rolling circumference (mm): 1920.8 Diameter (inches): 24.1 Diameter (mm): 611.4 Aftermarket tyre size Width (mm): 205 Profile (%): 45 Size (inches): 16 Sidewall (mm): 92.3 Actual speed at indicated 60mph: 54.9 Rolling circumference (inches): 73.1 Rolling circumference (mm): 1856.4 Diameter (inches): 23.3 Diameter (mm): 590.9
Last edited by Trappy; 26/06/2011 21:10.
F****** b****** thing...
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Re: P Zero 205 45 16's...
[Re: X19_pilot]
#1231151
26/06/2011 12:33
26/06/2011 12:33
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Joined: Dec 2005
Posts: 8,418 Lightwater, Surrey
DaveG
Club Treasurer Member 311
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Club Treasurer Member 311
Je suis un Coupé
Joined: Dec 2005
Posts: 8,418
Lightwater, Surrey
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205/45x16 are way too small, you need to go large!
225/45x17 is what I have on at the moment, with Eibach's and Billies. Get a small amount of rubbing on the wheel arch liner on full lock but otherewise they're great, almost eliminate speedo error and fill the arches much better.
Trye OD is 634.3mm compared to 611.4mm or standard 205/50x16 (608.9mm for 225/45x16)
If and when I go back to 16's, I will try 205/55x16 or 225/50x16 but the 205/55x16 size is the cheapest size you can get
1996 Portofino 20vt & 2000 Pearl White Plus 1985½ & 2016 2017 Fiat 124 Spider + XF Sportbrake
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Re: P Zero 205 45 16's...
[Re: Edinburgh]
#1231156
26/06/2011 12:44
26/06/2011 12:44
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Joined: Feb 2006
Posts: 5,390 Essex
Trappy
Forum is my life
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Forum is my life
Joined: Feb 2006
Posts: 5,390
Essex
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Trappy how much do you charge for a 225/45/17 readout ? Width (mm): 225 Profile (%): 45 Size (inches): 17 Sidewall (mm): 101.3 Actual speed at indicated 60mph: 59.2 Rolling circumference (inches): 78.5 Rolling circumference (mm): 1992.7 Diameter (inches): 25.0 Diameter (mm): 634.3
Last edited by Trappy; 26/06/2011 21:09.
F****** b****** thing...
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Re: P Zero 205 45 16's...
[Re: X19_pilot]
#1231250
26/06/2011 21:00
26/06/2011 21:00
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AP1
Unregistered
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AP1
Unregistered
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Great calculations but UK speedos must legally show the correct speed or overread. Most overread.
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Re: P Zero 205 45 16's...
[Re: ]
#1231254
26/06/2011 21:14
26/06/2011 21:14
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Joined: Feb 2006
Posts: 5,390 Essex
Trappy
Forum is my life
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Forum is my life
Joined: Feb 2006
Posts: 5,390
Essex
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Great calculations but UK speedos must legally show the correct speed or overread. Most overread. I see what you mean, I put it the wrong way around earlier and have now updated (in bold). All of the above tyres will overread, i.e. show a speed higher than you are actally travelling at. I honestly don't think tyres big enough to correct the speedo inaccuracy of these cars, or indeed make it underread, would fit in the arches...
F****** b****** thing...
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Re: P Zero 205 45 16's...
[Re: X19_pilot]
#1231266
26/06/2011 21:32
26/06/2011 21:32
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Joined: Dec 2005
Posts: 8,418 Lightwater, Surrey
DaveG
Club Treasurer Member 311
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Club Treasurer Member 311
Je suis un Coupé
Joined: Dec 2005
Posts: 8,418
Lightwater, Surrey
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Well I reckon that with standard 205/50x16's at a "real" 70.0mph (by GPS) my speedo reads 74.9 which is a +7% error (maybe the error was reduced on later versions?).
205/55x16 will halve the error to 3.5% (72.5mph indicated) and 225/50x16 is similar (3.6% error, 72.5mph)
225/45x17 reduces the error to 3.1% (72.2mph) which is enough for me, I know from experience that around 635mm OD is the largest you can go, so for example 205/50x17 takes the error down to zero, but OD is 657mm. Dunno if you can even get that size though?
And of course the larger you go, the higher the car sits off the ground, by 11.5mm in my case with the 225/45x17's
But as the Yanks would say, YMMV*
* your mileage may vary
Last edited by DaveG; 04/07/2011 10:34. Reason: correction, I have 225/45x17
1996 Portofino 20vt & 2000 Pearl White Plus 1985½ & 2016 2017 Fiat 124 Spider + XF Sportbrake
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Re: P Zero 205 45 16's...
[Re: Trappy]
#1231278
26/06/2011 21:50
26/06/2011 21:50
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Joined: Mar 2007
Posts: 16,842 Auld Reekie
Edinburgh
Club President, member225
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Club President, member225
Forum veteran
Joined: Mar 2007
Posts: 16,842
Auld Reekie
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Trappy how much do you charge for a 225/45/17 readout ? Width (mm): 225 Profile (%): 45 Size (inches): 17 Sidewall (mm): 101.3 Actual speed at indicated 60mph: 59.2 Rolling circumference (inches): 78.5 Rolling circumference (mm): 1992.7 Diameter (inches): 25.0 Diameter (mm): 634.3
BumbleBee carer
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Re: P Zero 205 45 16's...
[Re: X19_pilot]
#1231681
27/06/2011 20:27
27/06/2011 20:27
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Joined: Oct 2009
Posts: 1,179 Sheffield
X19_pilot
OP
Enjoying the ride
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OP
Enjoying the ride
Joined: Oct 2009
Posts: 1,179
Sheffield
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Some great feedback there guys..... as usual Since I have just had a shed load of work done to her, I am not on great speaking terms with my wallet, so 17's are not an option yet. The Toyo's in the standard size seem favourable on most counts - if I can still get them, if not it will be my original second choice... Falkens. No experience with either but you guys rarely get it wrong. Cheers all.
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Re: P Zero 205 45 16's...
[Re: X19_pilot]
#1231928
28/06/2011 14:52
28/06/2011 14:52
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MikeRoss
Unregistered
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MikeRoss
Unregistered
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I wouldn't have the toyos, personally. Had a set on a mondeo and they wore very very quickly.
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Re: P Zero 205 45 16's...
[Re: X19_pilot]
#1232105
28/06/2011 23:53
28/06/2011 23:53
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Joined: Feb 2006
Posts: 5,390 Essex
Trappy
Forum is my life
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Forum is my life
Joined: Feb 2006
Posts: 5,390
Essex
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The one thing I cant get my head around, is Pzeros are fitted to many high performance cars with strong reviews, how come this size gives poor performance? Does the tread pattern change with different sizes? I think P Zero's are very old technology now (standard on the 20vT in 1996). I'm sure there are later updates (like Nero and Corsa) that are the better ones, but I'm possibly talking shite and can't be bothered to look for proof
F****** b****** thing...
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