Thx Andy, I have my 2004 RR V8 for off roading with 19" wheels and All Terrain tyres, its a machine for off road use, although it is getting a bit battered now, but it is worth nothing, so really happy to use it for what it is designed for

Last edited by pcourtney on 15th Jan 2024 10:30pm. Edited 3 times in total

Hi,

If you are planning on mixing profiles you need to be aware that you'll not be covered by warranties and you could well have insurance issues.

I used to run Scooby's and Subaru used to winge even when the tyres were worn unevenly, and were really hot on tyre rotation, apparently a difference in tread depth of just 3mm would put strain on the diffs.

If all were manual with no electronic controls then no problem, you might get a bit of whine, but when these complex automated systems are at play they use the different rotational rates for quite a lot of things. They use it to detect wheel slippage if wheels are rotating at different speeds and can confuse or even put the car into limp home mode. They get used for tyre under inflation warning systems, i.e. tyres are rotating at different speeds means the rolling radius is different ergo one of the tyres must have low pressure. I'm sure a whole host of other stuff.

Anyway, you can run different profiles for sure, notwithstanding the insurance and warranty issues, but what you cannot have is a difference in rolling radius of more than a couple of percent or youre going to face mechanical problems.

Andy Fuji White / Jet 2012 4.4 TDV8 Westminster

Mine wear pretty evenly front to rear but alignment, bush condition and driving style will influence this and if you are getting uneven wear then it's wise to rotate front to rear. Difference in rolling radius between a new tyre and one that needs changing is (3/4mm for me) is way less than the difference between a 255/55 R20 and 255/50 R20. 2012 TDV8 Vogue (L322)

Hi,

I know I go over the top on some subject, but this time not, I'll simply leave you with this and you can imagine the thrilling 200 page report that accompanies it.





Cheers

Andy Fuji White / Jet 2012 4.4 TDV8 Westminster

I bought some secondhand wheels that had 255 55 20 tyres fitted and the steering felt a bit vague and the ride felt to compliant, and they followed grooves and lines in the road. I replaced them with 255 50 20 tyres and the ride just felt tighter and more positive.

Same brand and model of tyre? 2012 TDV8 Vogue (L322)

Going back to my post about transmission wind up and fisha's very comprehensive reply. All diffs are designed to accommodate the slight differences in rotational speed of the wheels when on the road. I would submit that on any ordinary road (not motorway) and in town the wheels are almost constantly all revolving at slightly different speeds (certainly more than 1%), so the diff/diffs is/are pretty much constantly in operation. I fully accept that Torsen (constant torque) diffs work differently, but they must also take into account this constant difference in rotational speed. LSD's are usually set at around 40% slip (some being 25%, but not less for road use), so there is no lock up under normal rotational speed differences.

It's just that I've never really been convinced about this 'issue' and need to understand it better before I am. Drives:
2010 FFRR TdV8 Vogue - Stornoway Grey
2010 FFRR TdV8 Vogue SE - Zermatt Silver
1998 BMW E36 M3 GTII

kevinp wrote:

I bought some secondhand wheels that had 255 55 20 tyres fitted and the steering felt a bit vague and the ride felt to compliant, and they followed grooves and lines in the road. I replaced them with 255 50 20 tyres and the ride just felt tighter and more positive.

That's exactly what I am also hoping for Kevin, good to know

The very latest L322's ( circa 2011/12) were all shod with 255 50 R20's , they must have thought at JLR HQ that this helped with a slightly better driving experience - otherwise why do this ??

The lower the profile the more pronounced any tramlining will be
New tyres always feel better for a variety of reasons - wear, age, manufacturer improvements.
L405's came with 255/55 R20 as standard so why did they not stick with 50 profile if they were superior? 2012 TDV8 Vogue (L322)

That's interesting, JLR going back to 255 55 R20's

It will partly depend on keeping the rolling radius similar across all the possible wheel diameters - eg the L405 was available with 19-22 inch wheels.

JayGee wrote:

The lower the profile the more pronounced any tramlining will be
New tyres always feel better for a variety of reasons - wear, age, manufacturer improvements.
L405's came with 255/55 R20 as standard so why did they not stick with 50 profile if they were superior?

The tread partern also makes a difference - were the tyres same brand and model? 2012 TDV8 Vogue (L322)

Last edited by JayGee on 11th Jan 2024 6:33pm. Edited 1 time in total

Yes, the tread pattern were all Pirelli Scorpion Zero's

Getting my calculator out, 255mm is approx 10" width of tyre on road

Profile is 50 - so 50% of 255 is 127.5mm x 2 = 255mm

Profile is 55 - so 55% of 255 is 140.25mm x 2 = 280.5mm

Difference in height between fronts and rears is 25.5mm ( approx 1 inch )

NB I have decided that an inch is probably beyond the L322's useful range, so have replaced
the rears today with 255/50 tyres, thank you everyone who contributed to this thread, what
seemed to me an option at first (or a misguided thought) has turned into a very useful discussion