Member Since: 31 Dec 2005
Location: South West
Posts: 23822
ronp wrote:
Don’t listen to them ….. they know not of what they speak.
[only kidding chaps ]
I’ve been running 20’s on my D3 and D4s and never experienced any issues.
However, I run with a wider tyre at 275/45/20 [GG AT3s] versus the standard 255/50/20.
And according to my man-maths, this gives me a bigger cushion of air to ride on ….. and even more than on the 255/55/19.
[just awaiting a mathematician to prove me wrong ]
Also, the extra width gives me more rim protection.
But, I don’t do “mud-plugging” (& wouldn’t do so on 20s), just forest & moorland track and the 20s have held up well with no punctures or damage.
And they’re great on the twisties.
(had 17s once on the D3 for off roading, but felt like i was running on blancmanges on the twisties.)
However, all this is just my experience & opinion.
Click image to enlarge
Ron-Either you or the online calculator is wrong!:
Each to their own, but I like to fit Land Rover oe size tyres on the smallest size rims that will fit over the front brake callipers.
It makes for a much more comfortable ride, less strain on the suspension components and harder to damage the rims against kerbs and rocks.2006 D3 HSE (Original & still the best)-GONE
2010 D4 HSE (A bit bling)-GONE
2014 D4 HSE (Almost too bling)-GONE
2015 D4 HSE (A heated what?)-GONE
2016 D4 Landmark (Written Off)-GONE
2016 D4 Landmark (Surely the last!) PD1881 rims-GONE
2017 FFRR SDV8 Autobiography (now semi-retired)
30th Mar 2023 11:50 pm
autobiorob
Member Since: 11 Jun 2014
Location: Peterborough
Posts: 161
Got 20s as standard on mine with no issues
31st Mar 2023 6:47 am
M3DPO
Member Since: 22 Sep 2010
Location: Notts.
Posts: 8223
I have a set of 19s that I use for winter with M&S tread pattern and a set of 21s that I use for summer, whilst the 21s look good and get many compliments they are no doubt a harsher ride and throw mud down the side of the car and take much more time to clean.
When I put the 19s on I always jokingly say to SWMBO “ I am looking for potholes now to go over them instead of looking for them to avoid”
Keep both sets and do what I do, buy a half decent battery torque wrench and it only takes 30 minutes with a trolley jack under the suspension arms to change them. It can when others can't,
It will when others won't,
It goes where others don't.
31st Mar 2023 8:01 am
ronp
Member Since: 29 Nov 2006
Location: North Yorkshire
Posts: 15263
RRSTDV8 wrote:
ronp wrote:
…… and I’ll raise you!
….. the 275 has three quarters of a inch extra width
Doesn't help ride comfort. Just means it tramlines more.
So more air per sq inch doesn’t aid ride comfort ?
Never had tramlining.
What type of tyre did you run when you experienced tramlining on the 275 ?...... always on the road less travelled 🚧
31st Mar 2023 8:38 am
RRSTDV8
Member Since: 07 Apr 2014
Location: Here
Posts: 13541
Sidewall depth gives better cushioning as there is some more flex available in the system. The pressures are the same in each tyre.
When I had 20s on my TDV8, they were 275/40 which was the correct size according to the book. I bought some 19s, fitted 255/50 winter tyres to them and found the ride felt a little better and the tramlining a little less. That was an increase of sidewall of about 15%. Then I fitted 255/55 on the 19s and the ride got better again as that's over 25% more sidewall over the 275/40/20.
But I notice that you're on 275/45 so you've already got a similar increase in sidewall as I got when I fitted the 255/50.
I hate to think how horrible the ride, etc., is with the 35 profile tyres some people run on RRS. It must be like Visiting from rrsport.co.uk
2012 RRS SDV6
2008 RRS TDV8
"When you fire that first shot, no matter how right you feel, you have no idea who's going to die! You don't know who's children are going to scream and burn. How many hearts will be broken. How many lives shattered. How much blood will spill, until everybody does what they were always going to have to do from the very beginning: SIT DOWN AND TALK!"
31st Mar 2023 8:54 am
ronp
Member Since: 29 Nov 2006
Location: North Yorkshire
Posts: 15263
I'm going to do my man-maths re "cushions of air" & put down some numbers and open this for thought.
It's not that I'm convinced, it's possibly just my wayward thinking...... could be right, could be wrong.
btw @ LT
That tyre calculator is more to do with - width v sidewall height v over rolling radius.
And granted that the sidewall on my 275/45 is shorter than that of the 255/50, but only by 4mm.
But that's into "tyre wear" territory and maybe "tread height" as an AT tyre starts of with 12mm blocks of tread v a road tyre with 8mm ...... but don't know if the sidewall height is calculated to the carcass surface or the total height inc tread.
But as said above, my point was in air per sq inch in a tyre e.g. my "cushions of air"... not sidewall height....... always on the road less travelled 🚧
31st Mar 2023 9:40 am
RRSTDV8
Member Since: 07 Apr 2014
Location: Here
Posts: 13541
I would think that mass of air is more important than air/sq in. You could, after all, have a tyre that has a wide tread but almost no sidewall and it would be rubbish for ride comfort but give very sporty handling. A similarly wide tyre but with a square cross section would be very good for ride comfort (unless fitted with a bit knobbly MT tread, of course) but horrible for handling. The mass of air acts as a spring - just like in our air suspension. It's the spring effect that messes with the handling but improves primary ride. Visiting from rrsport.co.uk
2012 RRS SDV6
2008 RRS TDV8
"When you fire that first shot, no matter how right you feel, you have no idea who's going to die! You don't know who's children are going to scream and burn. How many hearts will be broken. How many lives shattered. How much blood will spill, until everybody does what they were always going to have to do from the very beginning: SIT DOWN AND TALK!"
31st Mar 2023 9:58 am
LT
Member Since: 31 Dec 2005
Location: South West
Posts: 23822
In layman’s terms and from personal experience, I find a deeper tyre sidewall improves ride quality, helps to prevent rim damage.
It also allows more scope to run low pressures to better handle some off road conditions. Although to be honest I’ve not had to that for years, as the TR system is so good and I’ve yet to drive any significant distance over sand.
I could be wrong, but I think a deeper sidewall must be less stressful on suspension components.
2006 D3 HSE (Original & still the best)-GONE
2010 D4 HSE (A bit bling)-GONE
2014 D4 HSE (Almost too bling)-GONE
2015 D4 HSE (A heated what?)-GONE
2016 D4 Landmark (Written Off)-GONE
2016 D4 Landmark (Surely the last!) PD1881 rims-GONE
2017 FFRR SDV8 Autobiography (now semi-retired)
31st Mar 2023 10:10 am
RRSTDV8
Member Since: 07 Apr 2014
Location: Here
Posts: 13541
A deeper sidewall does increase undamped motion in the system, however. Whether that hurts the components is beyond me.
As for airing-down, I'm not sure that's a good thing to do with LR tyres these days - they're all too short in the sidewall to allow much airing-down without risking sidewall pinch. Interestingly, when a well-known off-roading youtuber took a D4 over a pass in South Africa, he did the exact opposite - he aired up to maximum allowed pressure in order to prevent any sidewall pinch happening. And he got through ok. Visiting from rrsport.co.uk
2012 RRS SDV6
2008 RRS TDV8
"When you fire that first shot, no matter how right you feel, you have no idea who's going to die! You don't know who's children are going to scream and burn. How many hearts will be broken. How many lives shattered. How much blood will spill, until everybody does what they were always going to have to do from the very beginning: SIT DOWN AND TALK!"
31st Mar 2023 10:15 am
ronp
Member Since: 29 Nov 2006
Location: North Yorkshire
Posts: 15263
And here’s my man-maths (on tyre sizes discussed here), based on air per sq inch (NOT psi) = “cushions of air”
Cushion of Air = 1
255/50 = 3251
275/45 = 3403
255/55 = 3576
Ok, I accept that if you spread the air out horizontally then the dampening is going to be very poor.
However if you stack it all vertically, although it would be a super duper comfortable ride, the handling would be (as I mentioned earlier) like a blancmange and you’d be off the road at the first bend encountered.
So, a compromise would seem the best solution.
BUT ….. where does that compromise lie ????????
I assume there’s no scientific/mathematical answer, it’ll just be down to personal preference on comfort v handling.
So, each to their own personal preference.
...... always on the road less travelled 🚧
31st Mar 2023 11:08 am
LT
Member Since: 31 Dec 2005
Location: South West
Posts: 23822
I still think a smaller cushion is more “squishy” than a much bigger cushion with the same volume of stuffing inside.
But yeah, ultimately it’s just down to personal preferences. 2006 D3 HSE (Original & still the best)-GONE
2010 D4 HSE (A bit bling)-GONE
2014 D4 HSE (Almost too bling)-GONE
2015 D4 HSE (A heated what?)-GONE
2016 D4 Landmark (Written Off)-GONE
2016 D4 Landmark (Surely the last!) PD1881 rims-GONE
2017 FFRR SDV8 Autobiography (now semi-retired)
31st Mar 2023 12:49 pm
Prodigal Son
Member Since: 05 Nov 2021
Location: Rowlands Castle
Posts: 9
Wow, I have to say that the Disco 3 forum members are amazing: guys thanks for much for everyones comments and thoughts.
Ronp I think I'm with you on the face lift, rather use that money and time for other things
Love all the tech re cushioning, although a smaller side wall would decrease squishyness as the strength of the side wall will be far greater?
Now, I'm thinking of swapping both the 18 and 20's for 19's. Is there better tyre choice for the 19's does anyone know.
31st Mar 2023 5:59 pm
MorganD379
Member Since: 29 Sep 2016
Location: SA62 3PP
Posts: 425
darrind wrote:
I run 255/55/20 on my20 inch rims and find them a great compromise plus you get absolutely spot on readings on the speedo both cars were on 19s previously and I found 255/50/20 on the d4 a bit harsh
+1 run the same size on my D3
31st Mar 2023 6:26 pm
Prodigal Son
Member Since: 05 Nov 2021
Location: Rowlands Castle
Posts: 9
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