The Tyre Thread

[Brando47]

I've purchased of st george before. Only downside was it had no australian warranty. Was only warranty though them. So if you had a defect with a tyre and it was 50% worn. They would give you half the cost of the tyre back once you returned the tyre to them. If you had the same issue with an authorised reseller it would be a change over for new item.

Might have to look into it some more then, I see in the FAQ they have a guarantee that their tyres are new unless specified. For some of the prices you could get two sets for the price of one anyway.

Ozzy Tyres is just as cheap for some tyres and free shipping though, but their website is kinda dodgy. Their sale countdown timers are just random, just reset when they get to zero and the price isn't affected. And I swear they just marked up everything on the site by 100% and then put everything down as 50% off haha

[J]

thanks for that, well the standard tyre size is 195/ 60R15 and was replaced with the 205/ 45R17s when i changed wheels so would it just be easier to stick to the same tyre size?

faneca: Tell us all the sizes that are listed on your tyre placard, including the load and speed ratings e.g. 88H, and then I can work it out for you

[faneca]

faneca: Tell us all the sizes that are listed on your tyre placard, including the load and speed ratings e.g. 88H, and then I can work it out for you

I believe this is what your after?

Thanks J your help is appreciated

[Brando47]

I did up a spreadsheet that will calculate all the diameters for you, so you type in your rim size, table will update and you can find tyres that are a matching size to the stock ones. So to be legal it has to be between 600 and 630, and to get the same speedo readings you want to be as close to 615 as you can.

Link: https://www.dropbox.com/s/ane6eox8e0...Diameters.xlsx

[J]

Thank you Brando47. You've pretty much done the work for faneca!

Yeah 205/45R17 does appear to be the closest size to 195/60R15! However, my calculation for the diameters are slightly different...

195/60R15 has around 1854.79mm circumference i.e. 590.40mm diameter. So the legal range is between 575.40mm and 605.4mm.
205/45R17 has around 1858.72mm circumference i.e. 591.65mm diameter. So only 1.25mm greater!

But you can also legally fit at least the following sizes in 17 inch (as long as they actually do make tyres in this size; you have wheels with the correct and legal width and offset to suit; the track is not increased by more than 26 mm beyond the maximum specified by Holden/Opel; and you have no clearance issues etc.):

195/45R17 has around 1831.57mm circumference i.e. 583.01mm diameter. So 7.39mm less.
195/50R17 has around 1890.38mm circumference i.e. 601.73mm diameter. So 11.33mm greater.
215/40R17 has around 1821.02mm circumference i.e. 579.65mm diameter. So 10.75mm less.
215/45R17 has around 1885.86mm circumference i.e. 600.29mm diameter. So 9.89mm greater.
225/40R17 has around 1845.14mm circumference i.e. 587.33mm diameter. So 3.07mm less.
235/40R17 has around 1869.27mm circumference i.e. 595.01mm diameter. So 4.61mm greater.

So by my calculations, you CAN legally fit 215/45R17 given your standard tyre size (whereas it would be illegal for my Turbo...go figure!). It will actually make your speedometer/trip meter/odometer more accurate (based on the assumption that your speedometer is optimistic by default, as it is on mine). But bear in mind that because it is that much more bigger than the standard diameter, it may actually make your speedometer/trip meter/odometer pessimistic i.e. showing a lower speed/distance travelled than is actually the case...not good with so many speed cameras around!

[I know it may be possible to use a Tech2 etc. to just dial in the new tyre size in order to recalibrate the speedometer/trip meter/odometer, but it may be more hassle than what it is worth...]

In the case of my G Turbo, fitting 205/45R17 instead of the standard 215/40R17 makes my speedometer/trip meter/odometer pretty much spot on. That makes it a lot easier for me to keep the car just within the speed limit: it is far easier to keep the car right on the 60km/h marking than an imaginary, say, 62km/h marking. At least for me anyway!

[digifish]

FWIW: Yesyerday after seeing the sale, I just replaced some

Car Passat 2003, Tyre spec 205/55 R16 91W (sorry it's not an Opel my Astra doesn't need tyres yet)

Original: Continental ContiSportContact 2 50,000 km (wifes car sensible driver ).

Replacement: Potenza Adrenalin RE002

Result. Meh. Nice tyres but not significantly/amazingly/even very noticeably better than the tyres that came off it. Even vs 50,000 km old ones.

They feel slightly lighter on the steering (normal for new vs old rubber) and track slightly better in high speed corners ~ 110 km/hr. Also probably expected. Slightly more road noise (this is more mechanical transmission through the tyre into the car, not from the sound they make which I think is less).

digifish

[J]

Original: Continental ContiSportContact 2 50,000 km (wifes car sensible driver ).

Replacement: Potenza Adrenalin RE002

Result. Meh. Nice tyres but not significantly/amazingly/even very noricably better than the tyres that came off it. Even vs 50,000 km old ones.

Interesting review digifish. I wonder if you have been taking it easy until your RE002s have done a hundred if not a thousand kays or so?
[See "Running in your new tyres" in http://www.carbibles.com/tyre_bible_pg2.html]

There are probably heaps of other factors affecting things, such as:
* when your RE002s were made;
* whether your RE002s were stored in a cool and well shaded place before they were shod onto your car;
* whether you have experimented with different tyre pressures in these RE002s (from memory, my old RE001s seem to like higher than average pressures, and my RE002s appear to be the same), etc.

But if these RE002s cost you less to buy now than the CSC 2s 50,000kms ago, yet still perform similarly throughout its entire life, and last 50,000kms if not more, then I guess it would still be considered an improvement then, especially for the price you've paid for them...? Time will tell I guess...!

[Having said that, it does seem to me that the RE002s are "softer" tyres than the RE001s, albeit with better wet performance. But it could well be mostly due to my change in tyre size!]

[Brando47]

Thank you Brando47. You've pretty much done the work for faneca!

Yeah 205/45R17 does appear to be the closest size to 195/60R15! However, my calculation for the diameters are slightly different...

195/60R15 has around 1854.79mm circumference i.e. 590.40mm diameter. So the legal range is between 575.40mm and 605.4mm.
205/45R17 has around 1858.72mm circumference i.e. 591.65mm diameter. So only 1.25mm greater!

J, where did you get your calculations for the circumferences from? I can see how you get to those diameters with those circumferences, but if you're right then my spreadsheet is wrong :S

I first found the diameters directly (which you need to know to find the circumference) by doing the following (without getting too into the maths haha):
Find the diameter of the rim = (rim size in inches) x (25.4)
Find the height of the sidewalls = 2 x (tyre width) x (aspect ratio / 100)
and then add these two numbers together to get the total diameter.
So for 195/60/R15 that would be: 15*25.4 + 2*195*0.6 = 615mm
that would give a circumference of 615*pi ~ 1932.087mm

I checked my method against an online calculator when I did the spreadsheet and it held up so I'm not sure..

[Brando47]

Forgot to mention, I think for a 7.5" wide rim you want a tyre width somewhere between 205 and 245 (inclusive) to realistically fit, only know from reading around a bit since my rims are the same width.

[J]

J, where did you get your calculations for the circumferences from? I can see how you get to those diameters with those circumferences, but if you're right then my spreadsheet is wrong :S

@Brando47 I think you are right, and I am wrong

I blindly trusted the values from the tyre size calculator here:
http://www.carbibles.com/tyre_bible_pg4.html

A quick visit to the RE002 page shows that:
the 195/60R15 version should have an OD of 615mm;
the 215/40R17 version should have an OD of 605mm;
the 205/45R17 version should have an OD of 616mm;
the 215/45R17 version should have an OD of 626mm;
and so on.

I am sure the other tyres' pages should agree with your calculations as well

More importantly for @faneca: does the incorrect calculation affect my list of tyre sizes that could be legally run (based on the original of 195/60R15), besides the 195s (sorry I was not aware that faneca already has wheels that are 7.5" wide!)?