Thread: So how do I increase my tyre size without reducing articulation?

I've got about 10 000km left on my tyres and then I'll need new ones. I was going to use this opportunity to get some bigger ones (I like 7.5 16 or 235 85 16), and was wondering what tyre/lift combo I should go for.

Just remember that you increse the gearing by 10-11% with 235/85x16 or 750x16. It will be marginal for towing and the speedo will read slow . You need 4.11:1 crown wheels and pinions to restore gearing which are not cheap to buy or set up.

I recommend 245/75x16 which is the largest tyre to fit without a lot of trimming. On a Disco you will still have to trim the rear of the rear guards. gearing is incresed 6% which is bearable and on mine anyway makes the speedo exactly correct.

To repeat my post for 235/85 you will need a 1 inch body lift.
Spring lift is really irrelevant for tyre fit unless you increase the size of the bumpstop.
Regards Philip A

Originally Posted by long stroke

I looked into body lifts a while ago and decided they were going to cost alot more than $100
But if you could prove me wrong i could be interested

CHEERS TIM.

Go and buy a piece of 2 inch round solid aluminium rod. It should be the 10 times the length you want to raise it. You then have to buy 10 longer bolts and a small amount of flat rod to make the alterations to the seat belt tie downs. You will also want about 500 mm of 2 inch box tube for the body supports in the rear wheel arches and the centre of the chassis. I would be surprised if you paid any more than $100.

It has got away from the original subject,as I posted earlier for a daily driver lift kits,big tyres are a PITA.Mine is a school bus,shopping trolley,work vehicle,through the week and a bush,hunting vehicle on weekends and I had all the goodies but took them off.You would find that fitting 40-50mm springs with Billies or my choice Koni shocks to suit with 245 tyres will give you want you want and it will drive light years better on road to boot.While you are there give it a wheel alighnment and tighten all the under body bolts,front to back and replace any bushes that have movement. Pat

Originally Posted by r.over

Go and buy a piece of 2 inch round solid aluminium rod. It should be the 10 times the length you want to raise it. You then have to buy 10 longer bolts and a small amount of flat rod to make the alterations to the seat belt tie downs. You will also want about 500 mm of 2 inch box tube for the body supports in the rear wheel arches and the centre of the chassis. I would be surprised if you paid any more than $100.

It would cost less than $100 until you have to get an engineers slip for the illegal seat belt mod.Or do what you seem to have done and don't worry about it.I hope you don't have an accident resulting in a fatality. Pat

Originally Posted by PAT303

It would cost less than $100 until you have to get an engineers slip for the illegal seat belt mod.Or do what you seem to have done and don't worry about it.I hope you don't have an accident resulting in a fatality. Pat

Any body lift has to be engineered to be legal, so I am not sure what point you are trying to make.

I have not modified the seat belts. The seat belts bolt to the floor. However, under the floor there is a bolt that reinforces the bracket to the chassis. You have to make a simple mod to extend the bracket 2 inches.

This is hardly life threatening.

I am curious why you have focused on this small point. Why not the risk to life of raising any vehicle through increased instability. How about the reduced braking capability through bigger tyres. Or maybe bad handling through increasing the profile of the tyres. I am also sure someone mentioned modifying the front steering, trailing arms, etc. Also highly illegal without engineers certificates and can cause failures in those components depending on the quality of the manufacture. How about fitting longer brake lines that are non-genuine. Then we can get into the legality of changing diff ratios to 4.11's, etc, etc

Originally Posted by walker

Love this thread....very entertaining.


I think you are all missing the point!!!

Articulation is way over rated. Just put some bigger springs in then install lockers!

It was inevitable someone posted this.
It would have to be you or Rovercare to do it, though

Originally Posted by r.over

You will find that the 17.2 inch 220 lb springs were actually intended to go in the rear. I also thought that the discussion was around a discovery/range rover, now you want to bring in a 130 into it. But you have proved me wrong. That is, if you have a 130 you can get springs that are 2 inches longer and around the same compression.

As others have pointed out, if you go raise the vehicle you really need heavier springs to control the extra roll.

If you have 10 inch travel shocks, it means that the compressed length is at least 2 inches longer (depending on brand) than standard shocks. How have you restricted the axle to stop them topping out.

Sorry, I didn't realise it was a RRC/Disco only discussion. Aside from individual spring rates, the suspension works exactly the same on a 90/110/130.

If I had just wanted a 'lift' I would've either bought an off the shelf kit and compromised articulation, or engineered a body lift.
I wanted more travel, so chose appropriately longer springs with an appropriately longer damper and modified the damper mount (raised the towers) so that I gained the full benefit of the new spring and damper.
That particular spring happened to fulfil my criteria before I started getting coils wound to my specs.
What makes a spring front or rear specific if the rate, free length and loaded height indicate it will work ok in a given application ?
Land Rover have also plqayed swap the springs, specifying certain springs for the front on one model and the rear on another.

BTW, I agree with your original assertion that most all off the shelf 'kits' reduce articulation/travel by using a heavier rate spring that is usually the same free length (or worse, shorter) as the OE one it replaces, but it doesn't have to be this way.

Regarding roll, why do I have to increase my spring rate to compensate for the extra roll ?
Aside from the fact that I have reduced the transient rate of roll by using much higher low speed valving in the dampers, why would I need heavier rate springs ?
What is intrinsically wrong with a little extra body roll ?

The reason I pointed out about seatbelts is ANY mod is not legal fullstop.I would not give any person information like that on an open forum.Move them 2inches or 2feet it makes no difference.Anyway the thread is about a mild suspension mod,not body lift's,35'' tyres etc. Pat