255/35/19 tyre pressures

[GrolschUK]

These are the dimensions of each rim......... PCD - 5x112

size- -19x8.5

offset/ET - 35

centre bore - 66.45

I have tried gaining the suitable size of tyre to fit these dimensions online, unfortunately have come up so far with a big zero. I wonder if there is someone more technically minded on the forum able to shed some light?

A search on any tyre selling site for 255/40/Y19 should fit your wheels, I don't think the PCD, Offset or anything other than the rim dimensions will make a difference...
You should find you have the pressure ratings for that size on your door sticker too.

[gman11]

Thx Mark, although still confused around correct pressures. So many conflicting recommended tyre pressures. On a positive note though, the rims set the car off perfectly.

[wildbore]

These are the dimensions of each rim......... PCD - 5x112

size- -19x8.5

offset/ET - 35

centre bore - 66.45

I have tried gaining the suitable size of tyre to fit these dimensions online, unfortunately have come up so far with a big zero. I wonder if there is someone more technically minded on the forum able to shed some light?

OK, if the wheels are genuine Audi then the PCD and centre bore will be correct.

I can't comment on the offset; that information should be in the owner's handbook, though.

The 19" rim isn't available on the A6 any more but it is the standard fitment on the S6. The Wheel size is 19x8.5 and the fitment is the 255/40/19 tyre. This is the tyre you need to fit to your car to get the correct rolling radius for the A6 chassis. A 35 section tyre will be too small so your speedo will read incorrectly and your engine gearing will be out, it won't look as good in the wheel arch and it will invalidate your insurance unless you notify them that you have deviated from factory-fit specification.

[gman11]

The wheels are not genuine Audi, after market make YSM by all account.

[gman11]

I just contacted two separate alloy wheel specialists who informed me the correct tyre size for my rims are indeed 255/35/19. At least that is one thing less to be concerned about. Would that make more sense wildbore?

[wildbore]

I just contacted two separate alloy wheel specialists who informed me the correct tyre size for my rims are indeed 255/35/19. At least that is one thing less to be concerned about. Would that make more sense wildbore?

Not to me, but I am no tyre expert. Ideally, you need to know the wheel and tyre specifications for 19" rims for your specific model of A6 and for your specific model year of car, which I am sure would have had a 19" option available (I think the 19" option was only dropped at the facelift?). That information would be in the relevant brochure or your owner's handbook. As far as I can see, the correct tyre is the 40 profile but if I were in your shoes I would go on what Audi specified at the time and nothing else.

As a cross-check, there are internet sites that provide a rolling circumference for a given tyre size. I suggest you input your car's standard tyre size and then your desired tyre size for your new rims; they should be very close. If the figures differ then the tyre is not correct and you will have speedo error and gearing issues.

[wildbore]

Here you go, pop your current and desired tyre sizes in here:
http://www.club80-90syncro.co.uk/Syncro_website/TechnicalPages/TRC%20calculator.htm

[gman11]

Thanks wildbore

[GrolschUK]

I just contacted two separate alloy wheel specialists who informed me the correct tyre size for my rims are indeed 255/35/19. At least that is one thing less to be concerned about. Would that make more sense wildbore?

They may be the correct size for the rims, but they are not the correct size for your car.
I'm pretty sure any 255/?/19 tyre will be correct for the rims...

The /35 and /40 are the tyre profile... the smaller the number, the narrower the sidewall is.
Less sidewall means a smaller diameter for the entire wheel.
Smaller wheel, as Wildbore pointed out, means that the gearing, speedo, and odometer will be out.

I have an A6 with 19" wheels that came with the car from new.
The tyres are 255/40/19
The tyre pressures are 36 front, 35 rear on a 2.0 TDI Auto

[gman11]

Here you go, pop your current and desired tyre sizes in here:
http://www.club80-90syncro.co.uk/Syncro_website/TechnicalPages/TRC%20calculator.htm

Interesting. Standard 225/50/17 speedo deviation @ 100km/h is 5.7km/h. My 255/35/19 speedo deviation is 0.7 km/h. So the 19's are more accurate showing on the speedo as opposed to the 17's.

Tyre suspension comfort is obviously better on the 17's, but I can live with that. Who would have thought it eh?