Increase ground clearance

I've been looking here & there & everywhere to find a good & thorough article on the subject of fitting bigger wheels and its relation to lifting - which turned out to be quite difficult. It seems the experiences hasn't been systematized - but there's lots of postings on the subject on Forums - especially in the US. You'll find tables listing tyre sizes, and you'll find pictures of lifted vehicles - but it's more difficult to find information on the interesting question of how much lift do you would need to fit certain tyres. 

This short article should be read as an introduction and nothing more! I have not lifted my vehicle - it's bog standard. So there's no live, first-hand experience on this. Hopefully, it will provide at least some insight for newcomers... Nevertheless: there's some insightful links here... 

Anyone heed the call for knowledge? Please Mail me!

Under construction

The call for ground clearance

Main drawback for a Discovery in the rough stuff, is the general ground clearance. The standard fitment wheels (29") are rather small, compared to a Defender or a series vehicle (32"). Bigger wheels translate directly into improved ground clearance - also giving better angles. The tow hitch and the small wheels will let the Discovery behind, when the Defenders keeps going. But as any thing Land Rover - rectifying this lag-behind is all in the range of some tools and a wallet!!! 

For those still thinking a Range Rover is more capable in the rough stuff than a Disco, it's worth mentioning that the wheel wells are bigger on Disco than RRs, which means they will take bigger wheels before they're bottoming out and you're rubbing top of the well (this is only one of a lot of things improved by the designers after nearly 20years of  experience with the Range Rover).

Standard fitment for a Discovery series 1, is 205/80-16 or 235/70-16, which are some 28,9 inches high. Compared this with a Defender with standard wheels at say 235/85-16 which are at 32 inches, the Defender has 1,5 inch more clearance under the diffs. This is what stops the Discovery when Defenders move on into the deep ruts. 

The reason for fitting such smallish tyres, are of course the need to keep a low centre of gravity for mainly roadgoing vehicles - but the wheels fitted to RRs and Discoveries are still bigger than the opposition. And as a dedicated offroader manufacturer Land Rover has a joker up its sleeve: the huge amount of axle articulation make easy work of even big boulder crawling with standard fitment sizes. Nonetheless - improved clearance will improve the vehicles capabilities even more, and let the vehicle fly through areas beyond reach with standard sized wheels. Bigger wheels also translates into better traction.

There's always practical and economical considerations in every modification, so it's worth summing up everything connected before commencing any work - and checking every issue in detail with fellow Land Roverists having done same thing before as you intend to do. The economic side of it also calls for addressing the issues in this article whenever you're into changing tyres or springs or shockers - you won't like to invest in new springs this year and buying bigger wheels calling for taller springs next year... But you can fit taller springs this year and wait until next year when tyres wear out; but there's only some instances when you can fit bigger wheels this year and only next year fit taller springs.

Fitting bigger tyres

If you're fitting bigger than standard tyres, they might not fit the vehicle without modifications: trimming of fenders, adjusting steeringstops, higher bump stops etc. are often called for when going bigger. The bigger wheels "fills" more of the wheelwell, and might rub onto the top of the well. To prevent that from happening, you must fit higher bump stops, which restricts the axles upwards movement. Basically, the axle always moves freely up/down - restricted by two factors: length of shock absorbers, and height of bump stops. 

Restricting the movement of the axle means the vehicle will more easily lift a wheel - i.e. poorer traction, translating into poorer RTI (though still far above the opposition). You gain offroad competence by fitting larger wheels - and then loose some of it by restricting upward axle movement... Obviously you need to allow the axle to move more freely - as much as it did when it was on the standard tyres.  The correct height of the bumpstops are determined by the height of the wheel (from wheel centre to top of wheel-well or where-ever it's rubbing) - so whatever setup, you'll need bumpstops conforming to the size of the wheels fitted. To regain the upward axle articulation despite the restrictions of a taller bump-stop, you will need to lift the vehicle by fitting taller/longer springs (or adding spacers under the coils). 

The downward axle articulation is determined by the length of the shock absorber - the downward travel will be stopped by the shocker being to its full extension too early. To break even, you will have to extend shock absorbers by the same amount as your lift (though, the shockers must not bottom out when compressed, which will fast break the shocker). 

The discussion on height of bumpstop and length of shockers, are theoretical considerations which may not come into account on a specific setup. Not all bigger wheels will rub inside wheel well with a stock axle bump stop - usually there's something to go on the original setup. The length of shockers will not always limit the downward travel - or these factors will be of less practical importance.

Rubbing along the fenders are determined by the width of the treading - but this problem is easily rectified by slight cutting, which (when done properly) will not be visible for an inexperienced eye.

The John Barge site here and the Discoweb here describe different tyres and what work is needed on the vehicle, though these are not covering all issues you might run into with your vehicle and a specific setup. To my knowledge, this is the most thorough resources available on this issue.

Lifting

In general, there's no need to lift a vehicle if bigger wheels are not fitted (but longer springs give more articulation), and the amount of lift must take into consideration also length of shockers and brakelines, suspension angles etc. A lift of +1" usually create no problems, reportedly a +2" lift should also work with standard setup, but above that the lifting calls for longer brakelines and longer shockers. You should probably budget for brakelines and longer shockers if you're in the +2" segment. Lifting the vehicle is usually done by fitting taller springs or spacers under the springs, which is called a suspension lift. For seriously high lifting, there's the issue of "bodylift", meaning the body is lifted higher above the chassis by the fitment of new bodymountings; this is more of a specialist work. Taller springs means more articulation, meaning the good stock articulation is improved to become even better. So lifting also improves traction by increasing the ability to keep all wheels on the ground. Fitting taller springs means more sway and general instability - so stiffer (heavy duty) springs are used - which counters the effect of taller springs by restricting axle movement from the stiffness of the springs... Fitment of Medium or Heavy Duty springs (Old Man Emu is a make often cited), or using standard springs intended for other models (Defender), means the body will sit higher above the axles. This will make more room in the wheelarch for bigger tyres, thus gaining more clearance under the axles.

You'll also find more extreme versions, giving an articulation previously unheard of - utilizing extremely long coilsprings, extremely long shockers, modified angles throughout the suspension and drivetrain. These have more popularity in US than Europe, though systems are now being developed also in Europe (Scorpion Racing). These long travel systems allows the vehicle to crawl over huge boulders, partially overcoming some of the problems associated with low ground clearance, and partially allowing fitment of bigger tyres. These must be considered extreme setups for extreme use.

No cure-all

It seems a good proposition to increase the size of the wheels, but nothing comes cheap... The wheelarches, gearboxes, diffs, halfshafts, coils, shock absorbers, propeller shafts, steering and suspension geometry etc. etc. are all made to fit and suit wheels of a certain size - and moving up (or down for that matter) will turn into problems elsewhere. Bigger wheels might not fit wheelarches, might rub radius arms, will hit top of wheel well at full flex, change gearing (worse acelleration - better top speed), increase loads on the halfshafts, steering will not self-center anymore. These issues are technical, and can be addressed using tools and your innermost pockets of your wallet. But there's more to it...

And as the vehicle grows higher, it also raises its point of gravity - translating into feeling more unstable etc. Suspension specialists Famous Four says their +1" HD coils are for regular heavy duty towing or offroad clearance - and say  "you'll loose in road handling what you gain from using heavy duty springs", and +2" coils are "for specialist use only" and not advisable for road use... Some US owners claim better on-road performance over standard springs after the fitment of Old Man Emu HD springs of +2" height. Confused?

A caution and a call for experts!

Lifting the vehicle is a specialist issue, and the judgment of different propositions calls for expert knowledge. The fitment of wheels slightly larger, and maybe rather large, should be within the range of advice possible by internet/e-mail discussions; some of the better sites (like Expedition Exchange) offer thorough advice in articles on their sites - other companies calls for discussion by phone. You're strongly advices to work thoroughly on the subject and consult experts and other owners before commencing any work. 

It's advisable to ride lifted vehicles to get a "feel" for what it means for ride-comfort on road. Most Discoveries are daily rides, and are supposed to work as family transport as well as offroader-toy for daddy... Don't forget: a bog standard Discovery is capable of really dirty doings, going places the opposition will have to look at from a distance. Don't commence any lifting or fitment of large wheels until you have a feel for what the Disco can do as is, and make sure you really know what you want before commencing the work and purchasing new goodies.

The taller the lift, the more problems associated - as is the taller the wheels, the more problems... Anything and everything has been done before by someone else, so can be done. But it might turn out to become a huge project of revamping the whole vehicle, which was probably not why you started the process...

Sizes & makes of tyres

For a table of different wheel sizes and what you'll have to do to make them fit, go to John Barge site here and to the Discoweb here. Expedition Exchange has a tyre size calculator. The Disco2 site also has a tyre-calculator, with comments on Disco2-uses etc. 

Only 16" wheel rim sizes listed here, but also 15" wheels are available . Disco2.com has this article, splitting the alternatives into standard tyres (29inch), slightly larger (30-31inch), rather large (32inch), and oversized (33inch+); this article use this distinction for systematizing the information. A thread on the Expedtion Exchange Forum covers the issue of lifting pretty well, though the wheel-sizes are not an issue in that thread (which is why you lift the vehicle). This article  deals with Range Rovers, but gives a very thorough overview of experiences with different sizes, tyres and brands for RRs.

Deciding which size you would like to go for, it's worth mentioning that only half the increase in wheel size will be present under your diff. Moving up 1 inch in wheel size, give you 0,5 inch better clearance - as only 50% of the size is below diff, i.e. from hub-down, and the rest is from hub up where you don't need it - rather it's useless to a degree where it creates the need for butchering and for lifting the Disco... If you want +2 inches under the diff, you'll have to fit wheels 4 inches taller. Wanting an increase of 3 inches under diff, you'll need even 6 inches taller wheels... 

Beware: No tyre brands are the same when it comes to rubbing and need for trimming and so on (nor are any Land Rover identical) - so check the actual size on your vehicle before purchase of tyres of a disputably huge size! The taller and wider the tyre - and especially with of the tread, the more important to actually check it works!  And sadly, not all manufacturer make the sizes you want in the type of tyre you want... E.g. BF Goodrich does not supply A/T in 215/85-16...

This table shows the calculated tyresizes (which as mentioned above varies between manufacturers and between different models of tyres) gives an overview of some of the relevant sizes for Land Rovers (only 16" sizes covered), including what you gain in height over the stock tyre size:

Standard height (29")

Tyresizes: 205/80-16, 235/70-16,  225/75-16, 245/70-16, 255/65-16 and others

The tallest tyre not affecting anything, is 225/75-16. You'll gain some 5mm height under diff over stock tyres, and should experience no problems like rubbing, speed change or anything. This tyre is thus a very conservative way of improving traction and giving the vehicle a very slight lift under the diffs - shouldn't harm on road handling or anything. If you intend to go "just a bit off road", and not compromise on road performance, this tyre would be as far as you want to go. 

The wider tyres in this category might force you into some adjustment or trimming (as reported in a recent Discoweb posting), but are supposed to be a direct swap. 

Slightly larger wheels (30-31")

Tyresizes: 215/85-16, 245-75-16, 255/70-16, 265/70-16, 7.00-16 and others

For slightly larger wheels (30-31"), you're likely to encounter moderate problems (not all of these are even applicable on all wheels):

These sizes are reported not to need lifting (taller coils and/or spacers), but most people seem to have lifted their vehicles anyway for a more worked-through setup. Wider wheels call for more work than slimmer ones, i.e. trimming of wheel arches and adjusting steering stops. Discoweb has an article on trimming for larger tyres. Fitment of the wider options in this category without any adjustments, calls for rubbing.

Camel Disco trimmed for 7.00x16

215/85-16 is the tyre of this size reported having fewest problems associated. . 7.00x16 was the choice of Camel Trophy Discovery, and seems to have needed only rear wheel well trimming and trimming of front endcaps. A reasonable option for lifting, will be the use of slightly taller/stiffer coilsprings. A lifting of 1-2" are reported to need no change of shockers or longer brakelines. Wheels in this category seems to be the biggest size advisable if you don't want a specialist vehicle with expensive and extensive changes. Again: slimmer tyres give fewer problems than wider. Only slight modifications over the original setup's reported on these sizes, but vehicles and tyres differ, so it's worth checking.

Otto were shod with 245/75-16 august 2003. Rear wing took a cut that possibly were not needed (at least not this size of cut), but the steering stop one side needed adjustment. Read more here.  This is a size oftenly chosen by US Disco-owners, and gives a sensible lift under the diffs, while still not posing too much problems to make them fit or compromise too much. A bit bodywork is needed it seems, but several owners report fitting this size on a totally stock setup; I suspect though rubbing might occur when wheels are fully stuffed when offroading. The vehicle looks well balanced, even on stock suspension, and has a more aggressive stance.

This vehicle is on 245/75-16, and has a lift of 2 inches (taller springs). This is a moderate setup, but it seems the owner has done some butchering on his wheel wells, and there's also a modified bumper. On the Discocrazy-site, there's a thorough write-up on fitment of this tyre.

This Discovery has Old Man Emu (OME) springs: #751 front and #762 rear. These are rated HD, and will lift the vehicle ~1.4" at front and ~2" rear. Tyre size not reported on this, but justmight be into the segment of "rather large" 32 inch tyres. More info on OME-suspension lifts here.

Mike Peters has this article on the Discoweb on fitting 265/70-16

Rather large wheels: ~32"

Tyresizes: 7,50x16, 235/85-16, 265/75-16 and others

For rather large wheels (32"), you're likely to encounter more substantial problems, in addition to the above mentioned; for instance (not all of these will be applicable on all wheels):

These sizes seem to need some kind of lift: taller coils and/or spacers - they seem to call for 2" lift or more, but the reports are not accurate on this. The 7.50-16, as a fairly slim tyre, reportedly have fewer problems; RR-owners report only marginal rubbing at top of rear wheel at full articulation (which calls for taller bumpstops only), but then again: tyres differ between brands and types. Change of gearing will be necessary to regain acceleration and power, which must be considered a seriously involved job. Using these sizes, you're into standard Defender-height territory!!!

Fitment of these sizes without trimming of wheelarches might work on-road, but with increased flexing off-road, tyres will rub - and you might destroy a tyre or bend fender flares. The wider wheels call for more work than slimmer ones, i.e. trimming of wheelarches and adjusting steering stops. Terry West has an article on the Discoweb detailing fitment of 235/85-16, a tyre seeming to be a popular choice among US Discovery owners. 

This vehicle has a total of 4 inch lift (3 inch taller coils + 1 inch spacers). Size of tyres are not reported, but seem to be rather large or probably oversized... Not knowing the tyresize makes the picture less interesting than could have been, because the lifting in and of itself is not interesting - what you do the lifting for is to be able to fit taller wheels to increase ground clearance by fitting larger tyres.

Oversized wheels: 33"+

Tyresizes: 255/85-16, 285/75-16 and others

(Disco2 285/75-16)

Not covered in this article. This is really specialist work. Rovertym and other US-based companies does interesting conversions addressing any issue connected to the fitment of wheels this big. Going for these sizes includes what's mentioned on the 32" wheels + some more: reworking of steering geometry via new radiusarms, new propshafts and so on and so on.

Icelandic MonsterDisco