Omega Owners Forum

Omega Help Area => Omega General Help => Topic started by: johncol on 20 March 2010, 13:53:24

Title: Tyres suitability?
Post by: johncol on 20 March 2010, 13:53:24
Hi, my 2.0l saloon has its test next week and am strapped for cash at the moment. The tyres need changing but I have a good set lying around from a 2002 nissan primera. Whats on the miggy is 215/55z R16's and the primera's are 205/60 R16's. Would they work on it?
Title: Re: Tyres suitability?
Post by: cem_devecioglu on 20 March 2010, 16:50:10
                       diameter      circumference
215/55-16           643 mm         2020mm
205/60-16           652 mm         2050mm

difference in circumference is %1.5   not a big difference only your speedo will read %1.5 less but can be arranged via tech 2.. you can use them I think..
Title: Re: Tyres suitability?
Post by: dbr on 20 March 2010, 21:42:21
Quote
Hi, my 2.0l saloon has its test next week and am strapped for cash at the moment. The tyres need changing but I have a good set lying around from a 2002 nissan primera. Whats on the miggy is 215/55z R16's and the primera's are 205/60 R16's. Would they work on it?
Put them on. Who has ever had the size checked?  They just check tread and for damage don't they?
Title: Re: Tyres suitability?
Post by: 2woody on 22 March 2010, 09:41:39
there's only 1.7% difference in them

the diameter or circumference is not correct if worked out mathematically. Even if only for comparing one size with another.

the vehicle & tyre industry uses something more reliable - the "wheel revs per mile" figure.

for your two tyres, 215/55 gives 823 wrpm, whilst 205/60 gives 809 wrpm. there's not really much to choose from.

you might find that the car'll handle a bit better on the 205's, at the expense of some grip
Title: Re: Tyres suitability?
Post by: mudflap on 22 March 2010, 09:53:33
Do the speed and load ratings match?  I am not sure if a change of tyre size might be taken as a modification and could affect your insurance..?   :-?


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Title: Re: Tyres suitability?
Post by: cem_devecioglu on 22 March 2010, 10:48:20
Quote
there's only 1.7% difference in them

the diameter or circumference is not correct if worked out mathematically. Even if only for comparing one size with another.

the vehicle & tyre industry uses something more reliable - the "wheel revs per mile" figure.

for your two tyres, 215/55 gives 823 wrpm, whilst 205/60 gives 809 wrpm. there's not really much to choose from.

you might find that the car'll handle a bit better on the 205's, at the expense of some grip

http://www.miata.net/garage/tirecalc.html

that calculations are done by this site.. even if your tires pressures are 2-3 psi low all exact calculations will change.. and assuming the factory follows the real measurements..

Title: Re: Tyres suitability?
Post by: Grrrrrr on 22 March 2010, 22:03:39
My SatNav indicates that my speedo (at motorway speeds at least) is typically a couple of mph too low. So sticking thicker tyres on for a more comfortable ride might actually bring them into agreement?
Title: Re: Tyres suitability?
Post by: Entwood on 22 March 2010, 22:16:18
Quote
My SatNav indicates that my speedo (at motorway speeds at least) is typically a couple of mph too low. So sticking thicker tyres on for a more comfortable ride might actually bring them into agreement?


Speedo's are DESIGNED to show a higher speed than actual, rather than under read .. so when it says 70 actual speed is likely to be 67 ish .. this is because the law does not allow them to underread ... at all.

Satnavs CAN be accurate under certain conditions, and a lot depends on the sampling rate of the device. If you are traveling in a dead straight line, perfectly level, at a constant speed .. then chances are the satnav readout is accurate.  if ANY of those 3 details are varying (going around a corner, climbing a hill, speed changing) then the satnav will become inaccurate to some degree.

This is quite simply due to how it works out your speed .. it does NOT "measure" speed in any way at all ... it calculates a position (A) then at a specific time (T) later it calculates another (B). It then calculates the distance between A & B - in a straight line - and it knows the time taken .. so calculates a speed. If the satnav is a cheap one, or one designed for walking not driving, then the time T is a "large" one .. and if you were, for example, driving a curve, the satnav will assume you cut the corner, so it will "think" you have travelled a shorter distance .. thus your speed will indicate LOWER than actual ........  so if you thought you were doing 70 you might be actually doing 75 ...  bye bye licence ....   :)

Title: Re: Tyres suitability?
Post by: Marks DTM Calib on 23 March 2010, 09:56:54
Just be aware that the Omega should have 225 55 16's on it....