Just thinking about tyres and after reading through a few posts seems 275s get a bit close to the struts, am thinking 265 / 50 R20 to add a little width.

Standard 20inch rims.

Continental Cross Contacts and Pirelli Scorpions seem to be available in this size.

What I also don't get is that I found chat about 275 / 45 R20 being closest in diameter to the original 255 / 50 R20 But I'd have thought the width should have nothing to do with diameter overall so why wouldn't 275 / 50 R20 be identical to the 265 50 R20 in overall diameter?

Therefore just want to check with you clever people - would the 265 / 50 R20 be the same overall diameter to original? Or am I missing something?

Thoughts appreciated.

Thx, Greg Cheers, Greg
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2011 Vogue SE 4.4 with lots of toys in Stornaway

The second number is the aspect ratio which denotes the size of the sidewall as a % of the tyre width. For example, 255/50 has a side wall of 122.5mm (50% of 255mm width).

So, in your example, a 265/50 tyre would have a side wall of 132.5mm, an extra 10mm height. The 275/45 would have a sidewall of 123.75mm which is pretty close to the original 255/50.

Hope that makes sense.

Rob 2021 D350 Fifty Edition - Carpathian Grey
2017 4.4 SDV8 Autobiography (2021-2024) - Santorini Black
2012 4.4 TDV8 Westminster (2016-2021) - Santorini Black

Ok, the profile ratio 45/50/60 etc is a percentage of the width and gives the height of the sidewall.

So on a 255/50 the sidewall is 50%of 255 ie 127.5mm
On a 275/45 the sidewall is 45% of 275 is 123.75 so not much difference

275/50 would have a sidewall of 137.5 so quite considerably taller tyre than standard.

A 265/50 would have 132.5 around a 5mm bigger sidewall this more rolling radius.

Several folks have fitted 255/55 tyres which have a sidewalk of 140.25mm so it may not be too much of an issue...

It’s how you keep a rolling radius constant with different sized wheels

255/50/20, 255/55/19 and 255/60/18 are the standard sizes and all have very similar rolling radius which is made possible by having the larger sidewal as the wheel gets smaller.

Edit rob beat me too it..... There is nothing that can't be fixed with a hammer😜😜
FFRR 4.4 SDV8 Autobiography Santorini Black.
KIA E-Niro 4+
2021 Discovery 5 D300 MHEV commercial

ok thanks chaps. got the aspect ratio now!

So if I want a little extra width without changing overall OD / circumference - what size should I be looking at?

Mentioned on other threads are 275 / 45 R20 which makes sense now I understand the 45 is relative.

But there was mention of tight clearance to the strut using the 275s.

That could leave a 265/45R20 as a possibility, they are listed.

Do I need an "SUV" - presumably that 's a weight rating? Eg:
.

Click image to enlarge

Oh and what's the 108Y code mean? (I just picked the above as an example)

Cross Contact Contis are listed as 109H

Pirelli Scorpion Verde listed as 107V

. Cheers, Greg
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2011 Vogue SE 4.4 with lots of toys in Stornaway

Last edited by GGDR on 9th May 2018 12:43am. Edited 1 time in total

I think I need a degree in tyres.

Either that or just replace like for like!

. Cheers, Greg
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2011 Vogue SE 4.4 with lots of toys in Stornaway

Number is the tyre load index and letter is speed rating of the tyre
You can go higher than the standard tyre's marking but not safely lower 2007 Vogue TDV8 in Zermatt Silver with Charcoal

gonna go

Can't help on the clearances and diameters, but these links may assist on the tyre markings:

https://haynes.com/en-gb/tips-tutorials/yo...-explained

https://www.oponeo.co.uk/tyre-article/wint...e-m-s-mark

https://www.tyrespeedrating.co.uk/

Richard

Greg,
Just a word of warning if you are thinking of changing to a different tyre size.
I have recently fitted 255 55 20 on Style 502 wheels and they are a real struggle to fit the spare in the wheel well.
Also Nino has told me that he has done similar with F1 tyres and that won’t go in the well when inflated.
Personally I like deep profile tyres for the extra comfort on potholes and rough roads.
Mike. G reg 2.5VM Vogue Portofino red 1991- 1999
V reg 2.5td P38 Rioja red 1999- 2006
53 reg td6 Vogue Oslo blue 2006- 2015
11 reg 4.4 TdV8 Vogue SE. Baltic blue 2015- date.
https://www.fullfatrr.com/forum/topic56162...tty+affair

northernmonkeyjones wrote:

Edit rob beat me too it.....

Only just NMJ......

Greg, take a look at this site. I've found it useful to compare wheel/tyre sizes in the past.

https://www.willtheyfit.com/

 2021 D350 Fifty Edition - Carpathian Grey
2017 4.4 SDV8 Autobiography (2021-2024) - Santorini Black
2012 4.4 TDV8 Westminster (2016-2021) - Santorini Black

Mine came to me running 275/45r20 on the Style 19 wheel (including spare), and I haven't noticed any issues so far, although admittedly haven't driven an FFRR on any other tyre sizes...

265/50r20 fits fine no issues. I used to run that size.
Generally 275 wise fits ok too
285 May need a spacer V8 or else ...

On an L322 I would definitely go 275/45/20 - no issues and as near as OEM in diameter you will get for a wider tyre 2021 L405 Vogue SE 4.4 V8 DIESEL ~ #17

Ah thanks chaps. That website https://www.willtheyfit.com/ is very cool Rob, thanks.

I want to keep the OD as close as possible (mike thx for the wheel well note) so a quick run of my options gives:

255/50r20 diam=763mm original

265/45r20 diam=746.5mm speedo error=2.21% (60mph = 61.33mph)

265/50r20 diam=773mm speedo error=-1.29% (60mph = 59.22mph)

275/45r20 diam=755.5mm speedo error=+0.99% (60mph = 60.6mph)

275/50r20 diam=783mm speedo error=-2.55% (60mph = 58.47mph)

I'll have a think. Either of the latter I'd have thought would do, leaning towards the 265s at the minute. Would fill the arches but I'm actually only after a bit of extra width. I want a nice ride so also reluctant on the 275s because of the 45 profile. Does that mean I'm getting old?

I regards to any insurance "altering spec" thinking (which I found on other posts, as long as I stayed at or above the current speed and load ratings, I'd have thought the rest wouldn't matter, no?
.

Last edited by GGDR on 10th May 2018 11:37pm. Edited 1 time in total

I’ll say it ... 275/45 looks cause it’s a smaller diameter

Makes the wheels look too small in the arch. V8 or else ...