So i had a major issue develop on my sport but couldn't pin point exactly when it came to light due to the speed it was occurring and me not using the car that often or at speed.

The symptoms where the car would change up 1,2,3 then hold 3rd till around 4000rpm, then hold 4th till the red line, then change up after that fine (but by now your going very fast).

If i went from D to Dsport and back to D it changed up, in manual it changed fine.

Now i've spoke to 2 different landrover specialist who both said along the line of a new box, or at least it sounded major. I've trawled here disco 3 etc with no joy then eventually came across an american based forum with the same problem, and someone said that odd tyre size or odd tyre brand or odd wear to the front tyres would cause a major problem with the car knowing when to change gear as it thinks its cornering. I took it all with a pinch of salt and went outside to find the front pair of tyres were not a pair (same size different make) the rears were a matching pair, so i decided to rotate the tyres round and the car is cured, shifting as smooth as ever!!

the problem wasn't noticeable under 50mph as the revs were low enough to not notice it, also i'm presuming the tyre was on the back and at some point when the wheels have been off its ended up on the front, all tyres were new on the car when i bought it.

the difference between the 2 tyres that had the same size written on the side was 1"+ in height so quite what the circumference difference is i arn't sure, but i found that if the speed sensors detect a 1km/h difference between wheel speeds this occurs.

i've enclose a pic and hope this may help someone in the future.




Last edited by shadrack on Tue May 06 2014 9:36pm. Edited 1 time in total

Cracking advice - well done  16MY Estoril Blue SVR.............
17MY Autobiography Dynamic - Corris Grey - WOW.
14MY Autobiography Dynamic - SDV6 - Fuji White
12MY Autobiography - SDV6 - Santorini Black - Dual View - Rear Entertainment - Sunroof.
12MY Autobiography - SDV6 - Orkney Grey - awesome ;(
2005 Java Black - 4.2 V8 Supercharged First Edition- will never be forgotten ;(

Well done

I love the cheaper fix's

mine just gone in to get fixed , hope its not my tyres lol

^^^^^^^ CD - I thought you was an MOT Tester  16MY Estoril Blue SVR.............
17MY Autobiography Dynamic - Corris Grey - WOW.
14MY Autobiography Dynamic - SDV6 - Fuji White
12MY Autobiography - SDV6 - Santorini Black - Dual View - Rear Entertainment - Sunroof.
12MY Autobiography - SDV6 - Orkney Grey - awesome ;(
2005 Java Black - 4.2 V8 Supercharged First Edition- will never be forgotten ;(

well im ordering a new pair of tyres for the rear now as i cant see that difference in tyre size been any good on the rear diff, but yes well happy with buying 2 tyres instead of a gearbox!

i will sell these tyres as they have 8mm+ they are pretty much as new, quite why 3 of one make and 1 of another were fitted as they were new before i got it as thats one thing i noticed that either the previous owner or the garage had put a full set on to sell it ( or as its turned out 4 new tyres not a set)

This difference between makes was pointed out to me by my tyre guy. I was surprised when he told me that different makers with the same size can give markedly different actual tyre sizes. Seems you've demonstrated that he was correct  2012 SDV6 - it's missing a couple of cylinders
2008 TDV8 - it was a labour of love and is much missed

Difference in tyre dimensions of the supposedly same size is something I discovered a few years ago when running a Volvo S60 fitted with optional sports wheels and lower profile tyres as a company car. The car came with Continental tyres and on the first tyre change the contract hire company insisted that a different make was fitted. It became immediately obvious that the front tyre were rubbing the inner arch on full lock and, following discussion with Volvo they stated that all tyres of that size would foul the arch with the exception of Continentals.

Fast forward a few years and the Toyo 888 tyres on my weekend toy are significantly wider than other makes of the same size

shadrack wrote:

the difference between the 2 tyres that had the same size written on the side was 1"+ in height so quite what the circumference difference is i arn't sure, but i found that if the speed sensors detect a 1km/h difference between wheel speeds this occurs.

Quote:

A +/- 1 inch difference is about the same as running one as 275/40/20 and the other as 275/45/20. (Or one as 255/50 and the other as 255/55 on a 19 inch rim.) Not something anyone would normally recommend!

I wasn't suggesting you would mix sizes on purpose, I was responding to your saying you weren't sure what difference an inch difference in size would make.

When I bought my RRS I did notice that one of the front tyres looked odd. On closer inspection, there was damage to it that wasn't especially obvious to the quick glance. The garage replaced it and did the other side too because that was close to worn out.

I have no doubt that if I hadn't noticed it they would have sold it to me as it was - the tyre dressing showed that someone had been close to the tyres at some point...!

It's annoying that the first responses you got were "new gearbox needed" because it would have been expensive and left you with the original problem. Typical of many garages these days it seems

Well done for sorting it out  2012 SDV6 - it's missing a couple of cylinders
2008 TDV8 - it was a labour of love and is much missed

this variation in makers sizing puzzles me too !

Each time I go into River Island and get a size 32" jeans, they never fit, but the Hugo Boss store's 32" are a great fit ! Wife says I should stick to the £30 River Island jeans in size 34" - but what does she know ! Lol  RR Sport Supercharged Vesuvius Orange 4.2 V8 First edition

Prefer RR Vouge S/C but they don't do Orange !

RRSTDV8 wrote:

I wasn't suggesting you would mix sizes on purpose, I was responding to your saying you weren't sure what difference an inch difference in size would make.

When I bought my RRS I did notice that one of the front tyres looked odd. On closer inspection, there was damage to it that wasn't especially obvious to the quick glance. The garage replaced it and did the other side too because that was close to worn out.

I have no doubt that if I hadn't noticed it they would have sold it to me as it was - the tyre dressing showed that someone had been close to the tyres at some point...!

It's annoying that the first responses you got were "new gearbox needed" because it would have been expensive and left you with the original problem. Typical of many garages these days it seems

Well done for sorting it out

no problem, i just hope someone else benefits from my countless hours trawling the internet, as you say i could have spent all that on abox rebuild and i would have had the same issue!!

Well done Shadders, great detective work I'm sure this has save you and many others ££££'s. I'll make this a sticky for you and the rest of our members.

This is the very reason i always swap 4 tyres at a time on any 4wd car i own, be it a performance car, or 4x4.

Great post Shadders