I have just noticed that the tyres on my 57 plate RRS TDV8 seem at odds to the handbook...

The car had 2 new tyres fitted by the dealer when I collected it (275/45/20) whereas the handbook lists the sizes as 275/40/20 - they are also 275/45/20 on the rears so at least they are all the same size - I just find it odd the dealer would put a non specified size on the car.

So, 2 questions.

Should I be concerned?

What pressures should I run in these (car normally transports 2 adults, 2 kids + dog and other rubbish?

Thanks kindly  Wife's Car: BLACK RRS TDV8 HSE with all the bits
My Car: Lotus Exige S2 PP & TP )

Generaly no issue with the larger size tyres. But if it was me I would be requesting a correct size dimension from the dealer...

C10KO wrote:

Generaly no issue with the larger size tyres. But if it was me I would be requesting a correct size dimension from the dealer...

Thank you - I think I will take it up with them.

In researching, I just came across this handy little website that visually shows you the differences a change in profile makes - very interesting. http://www.kouki.co.uk/utilities/visual-tyre-size-calculator


I'm guessing that having a taller profile actually makes the ride a little softer (at the detriment to handling).

Thanks for the reply so quickly - interested in whether anyone else is running these sizes - a search suggest not  Wife's Car: BLACK RRS TDV8 HSE with all the bits
My Car: Lotus Exige S2 PP & TP )

Some people on here do and they report good feedback. The size dim is equal to 255/55/19 which LR used for the G4 vehicles so there should be no technical problem but can see it being an issue if you happen to be in e.i. an insurance or waranty situation.

Good point ref insurance - I will ask the question.

I've already had some warranty work done (ARB Bushes and Mass Damper kit) all fitted under warranty and in fact is back again tomorrow for 3 days for an intermittent Suspension fault (they think one of the bags are leaking and need to disconnect everything apparently to see which is at fault - personally I think they don't have a clue as its been back twice already!)

Still, lets see in 3 days whether they get it fixed this time - 3rd time lucky and all that  Wife's Car: BLACK RRS TDV8 HSE with all the bits
My Car: Lotus Exige S2 PP & TP )

I noticed a few sites arent listing the correct size but do the size you had fitted...dont know why but i did wonder what would happen if i needed a tyre Mike

2014 Facelift Discovery

Interesting websire, note it also states:

Note: Changing your wheels/tyres will affect your speedometer reading!

• When your speedo reads 60mph you will actually be doing 69.9mph.

Supacat wrote:

Interesting websire, note it also states:

Note: Changing your wheels/tyres will affect your speedometer reading!

• When your speedo reads 60mph you will actually be doing 69.9mph.

its not quite as much as that,if you are doing 30mph you will actually be doing 31.1mph & if your doing 60mph you will be doing 62.3mph,but speedo's are slightly out anyway so it wont make that much differance.
check on here http://www.kouki.co.uk/utilities/visual-tyre-size-calculator
i use it all the time when people are putting after market alloys on their cars.
Andy. Gone,,TDV8 arctic frost,black leather,colour coded handles,rear entertainment,sunroof.
1980 Rolls Royce,shadow 2 in white.
Gone 07/57 TDV8 santorino,black leather.chrome handle's/mirror's.
Gone 02/52 FFRR vogue.

Interesting site. Like the calculator. Particularly like that 255/50/19 is actually slightly larger in diameter than 275/40/20. People put 20s on to "fill the arches" etc but they actually don't. Got to laugh!  2012 SDV6 - it's missing a couple of cylinders
2008 TDV8 - it was a labour of love and is much missed

RRSTDV8 wrote:

Interesting site. Like the calculator. Particularly like that 255/50/19 is actually slightly larger in diameter than 275/40/20. People put 20s on to "fill the arches" etc but they actually don't. Got to laugh!

The reason they fill the arches is because they are wider,

Andy. Gone,,TDV8 arctic frost,black leather,colour coded handles,rear entertainment,sunroof.
1980 Rolls Royce,shadow 2 in white.
Gone 07/57 TDV8 santorino,black leather.chrome handle's/mirror's.
Gone 02/52 FFRR vogue.

V8 andy wrote:

Supacat wrote:

Interesting websire, note it also states:

Note: Changing your wheels/tyres will affect your speedometer reading!

• When your speedo reads 60mph you will actually be doing 69.9mph.

its not quite as much as that

It is - if you click the link above and use the example tyre change on the same web site you quote

Supacat wrote:

V8 andy wrote:

Supacat wrote:

Interesting websire, note it also states:

Note: Changing your wheels/tyres will affect your speedometer reading!

• When your speedo reads 60mph you will actually be doing 69.9mph.

its not quite as much as that

It is - if you click the link above and use the example tyre change on the same web site you quote

so you are saying a 275/40/20 is doing 60 the 275/45/20 will be doing 69 when speedo shows 60 dont think so its only a couple of mph out.

Andy. Gone,,TDV8 arctic frost,black leather,colour coded handles,rear entertainment,sunroof.
1980 Rolls Royce,shadow 2 in white.
Gone 07/57 TDV8 santorino,black leather.chrome handle's/mirror's.
Gone 02/52 FFRR vogue.

V8 andy wrote:

so you are saying a 275/40/20 is doing 60 the 275/45/20 will be doing 69 when speedo shows 60 dont think so its only a couple of mph out.

Andy.

No

click the link you posted and a worked example popos up - 14" to 17" and thosearethe figs I quote as an example of the issue...