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Jwsturner

17" Tyre Size

8 posts in this topic

I currently have the upgraded 17" alloys on my car fitted with 205/40/17 tyres. They all need changing as does one of the alloys as it is buckled. I have read on other sites that I can change the tyres to 205/45/17 which will make the ride slightly comfier and may reduce further damage to the alloys. Has anyone else done this? Or is there an 'expert' in the tyre trade that can advise on this?

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with those tyres your car speedo will show less speed than what you are actually going... ;)

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That is not a Ford recommend size.

You should always try to keep within +/-2.5% when changing tyres - yours would be 3.37% (circumference of 1872mm increasing to 1935mm)

Also when your speedo shows 70mph you'll actually be doing 72.36mpg (http://www.alloywheels.com/Tyre_Calculator)

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I noticed while driving with the GPS on that my speedo reads about 5mph above the speed that the sat nav shows at 60 mph, I took note of what Les said about putting 45 tyres on instead of the 40 on 17" wheels that made me think as the fiesta Zetec S comes with standard 16 inch 5 spoke wheels (as mine has) but most upgrade to the 17" ones is that why my speedo reading is 5mph faster than the actual speed of the car? Or is all that compensated for by the 40 tyres on the 17" wheels.

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I noticed while driving with the GPS on that my speedo reads about 5mph above the speed that the sat nav shows at 60 mph, I took note of what Les said about putting 45 tyres on instead of the 40 on 17" wheels that made me think as the fiesta Zetec S comes with standard 16 inch 5 spoke wheels (as mine has) but most upgrade to the 17" ones is that why my speedo reading is 5mph faster than the actual speed of the car? Or is all that compensated for by the 40 tyres on the 17" wheels.

All car speedos read a bit high (about the same as yours)

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The standard procedure is to allow 10% of the posted speed limit but this can be disregarded by any Police Officer using handheld speed guns if they consider the driver is slamming on the anchors before they can get a reading.

Most Gatso units fire at 33mph in a 30 zone.

The annoying ones are the average speed zones where the cumulative readings are used, if you pass one unit at 34 then you need to pass the next at 32 or below or they will get you.

I probably trip Gatso's at least 5 times a week but as long as i'm on an authorised blue run it is lawful and justifiable and no further action is needed.

I just have to remember to lift the foot in my own car, sometimes i forget which car i'm in.. force of habit.

Just watch the camera vans as the operators are generally bored and bitter, twisted individuals. <_<

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Can't you get subsidised blues and twos for your own vehicles? That would solve the speed camera problem, and also enable you to get to the front of traffic queues easier. Maybe suggest it to the people in charge :rolleyes:. I'll take a set too :D.

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I do have a dashboard light for if I'm called for an emergency but there are strict guidelines as to the usage.

Pity really.

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