Original Tire Size?

[AlanV2]

Hi all,

Was wondering what the normal wheel/tire size combo was fitted to my car.

Car is a W220 (S320 CDI)
Current tires are 255 / 45 / 17

Reason for asking is that I have to drive the A80 everyday which currently has a 40mph speed limit while the current upgraded to motorway status is carried out (due to finish 2012) and I always seems to be going slower than everyone else.

I did see a "standard tire size" on a website somewhere, but wasn't 100% sure, anyway I put that size and the current tire size in to a tire calculator and think it said I would actually be going slower than the speed on the speedo by 2 or 3 mph.

Was wondering what the actual figure would be and it I can tell the car the right size or make ajustment ofr it?

The A80 has average speed cameras all the way along so don't really want to get a ticket for going too fast, so for now have stuck to the speedo reaing, much to the annoyance of other driver I would imagine.

Any ideas?

Thanks
Alan

 

[npuk]

225/55R17 for 17" x 7.5J if original Mercedes alloys

Alloy Wheels Direct Ltd | Fitting Chart Index

 

[AlanV2]

Thanks,

So if the standard wheels fitted at the factory were:

225 / 55 / 17

Current tires fitted are:

255 / 45 / 17

This website says that the ones I have on are 2.6% too fast, so when the speedo says 60mph (their example) - the car will actually be going 58.4mph.

Can I count on this when going through speed cameras?

Thanks
Alan

 

[Cen]

Thanks,

This website says that the ones I have on are 2.6% too fast, so when the speedo says 60mph (their example) - the car will actually be going 58.4mph.

Can I count on this when going through speed cameras?

Thanks
Alan

Speed detection devices also have a leeway tolerance for example if the speed limit is 40 mph then the tolerance would be 10% plus 1 mile an hour dependant on the local authority sometimes as much as 2 miles per hour.

Therefore the speed detection device would need to see you achieving 45 mph plus before issueing a ticket

 

[AlanV2]

Hi Cen,

Is that the same with avergae speed cameras? or just normal Gatso speed camera?

I just always seem to be going so much slower than everyone else, it happened in my old car too, but I just thought the speedo was off as it still had the stock wheels and tires on.

Thanks
Alan