Because I was interested in putting alternative tyres on my Discovery Series II, either as all-day runners or as an extra set for outings, I have gathered the following information about the various tyres, availability and feasibility for my type of car. I now am the pleased owner of 245/75R16 BFG MTs on RR alloys, fitting well on the inverted spare wheel carrier. WvD
Wheels are the metal (steel, aluminium, magnesium, or alloy) parts, and tyres are the rubber parts. Typically, there are five wheels on a DSII.
Stock tyres are 29 inch on 16 or 18 inch wheels. Obviously these fit well. Largest to fit on a stock DSII are 30.5 inch sized tyres, of which the 245/75R16 size seems to be the most often mounted. With a body lift of approximately 2 inch, 32 inch tyres may be fitted, of which the 265/75R16 are by far the most popular. Changing the spare wheel carrier is then necessary. You might fit even larger tyre sizes, but significant additional changes to your DSII will be necessary.
Changing the wheel diameter from 18 inch to 16 inch wheels (or going the other way around), and keeping the tyre width and the outer diameter of the tyre the same, will technically speaking not give larger tyres on the outside, but it will give you higher (or lower) tyre walls. More wall means flexibility, so that the tyre can better follow rough tracks and accommodate bumps for comfort, and get better grip. Less walls means less flexibility, therefore more direct steering. Typically, for off-road preference you choose the 16in wheels, and for on-road preference (yeah, right, in a Land Rover?) you would prefer the 18in wheels.
Increasing tyre width, keeping the rest (wheel, tyre
diameter, engine, etc) the same, will give you a larger contact
Increasing the tyre height, keeping the rest the same, will give you quite a few effects, some positive and some negative, depending on which way you're looking at it
Obviously the aforementioned effects are proportional to the tyresize increase that you have in mind. Increases by 5% (Slightly Larger, see below) are noticeable but quite acceptable. No special adjustment are necessary. Increases by 15% (Oversized) are very pronounced, and changes to gears, diffs, etc are hardly avoidable. Precise effects can be calculated with the tyresize calculator at the bottom of this webpage.
|29.0in||235/70-16||stock size in Europe and Oz|
|29.0in||255/55-18||stock size in US, optional elsewhere|
|29.1in||255/65-16||stock option worldwide|
Standard DSII tyre size. Obviously this size of tyres are plentiful around, and typical ones have a fairly balanced road/off-road bias, e.g., Michelin 4x4XPC, and BFGoodrich TracEdge.
The 16-inch wheels are standard issue worldwide on lower trim levels. Higher trim levels are equipped with 18-inch wheels as standard, because they give more car stability, especially in on-road situations. In the US, any model with ACE is automatically fitted with 18-inch wheels. Typical first tyre related upgrade, when supplied with 18-inch wheels, is to exchange them for 16-inch ones. The advantage is that with a particular outside wheel+tyre diameter, the 16-inch wheels have taller, and hence more flexible tyre sidewalls, and therefore offer more grip in off-road situations.
In many countries, the tyresize of a particular car is included in its homologation for that country. This results in it being illegal to mount any other tyresize (more than +1.5% or -2.0%) than originally mounted to the car. Since the DSII comes with a 29 inch tyres, the choices in those countries for alternatives are limited to the ones mentioned above.
|30.4in||215/85-16||Popular alternatives on RRs|
|30.5in||245/75-16||Popular alternative on stock DSII|
|30.6in||265/70-16||Technically the largest fit on standard DSII, but not a common tyre size|
|31.0in||7.50R16||Old LR style, narrow. Check for actual size|
Very reasonable alternatives. Often used on stock suspension without problems. But beware, people interested in these sizes tend to also change the suspension for lift and for improved ride.
The spare wheel carrier needs no adjustment for the 30-inch tyre sizes, but as it will be a close fit, allow for variation in Land Rover build and in practical tyre size, and measure for yourself. Wheels up to 30.5 inches may be expected to fit properly on a standard carrier (mine do fit exactly). The 31-inch tyres probably won't fit the carrier without adjustment, for which several alternatives are described below.
|31.5in||285/60-18||Large alternative for 18in wheels|
|31.6in||265/75-16||Often used alternative on lifted DSIIs.|
|31.7in||235/85-16||stock Defender size|
Rather large alternatives, and generally regarded as the largest reasonable tyre size for the DSII. It can be run on stock suspension, but expect rubbing on the radius arms on the wider ones, and even the narrow ones in off-road conditions (full lock). Also rubbing is to be expected on the inside of the wheel wells on the front wheel arch panel of the front bumper. Lift, bumper change (trimming or replacement), and adjustment of steering stops (or wheel off-set) are recommend for serious use. And note that widths larger than 267 mm (10.5 inch) will seriously rub car parts (fenders) and also extrude outside of the car body, which is illegal in many countries. On-road car handling is significantly altered.
Adjusting the spare wheel carrier is absolutely necessary for this size. Possible adjustments, all actually reported as really carried out by a DSII owner, include
The 32-inch tyres are the stock size for Defenders, and therefore there are plenty examples about, e.g., BFGoodrich AT or MT, Rover MT/R, Yoko Geolanders, and many others.
|32.6in||285/65-18||Not common, but they exist|
|32.8in||267/80-16||(actually 10.5in wide)|
|32.9in||32x9.5x16||Simex is slightly off in its designations|
|33.1in||255/85-16||Several people reported to have this on their DSII.|
|33.4in||295/75-16||Too wide. No reports|
|Things may seem scary below this line. That is only natural: they are scary! You're out of bounds here|
|34 in||8.25x16||Michelins (way off in its designation)|
|34.5in||315/70-17||Chevrolet Camaro wheels with practically an exact fit for DSIIs, daily driver, by Greg|
|35in||35x10.50x16||Yes, Greg made these Swampers SSR Radials 'fit'. Merely had to remove some loose sheet metal that was in the way.|
|35in||35x12.5x18||Nothing serious here, just adding some data for the 18in wheelers|
|36in||9.00x16||Michelin XL: trial fit made Greg chicken out. No other serious attempts reported|
|36.5in||9.00x16||Unbelievable: Greg fitted these too, and did the Globe tour with it. Note: Michelin XZL is way off with its designation here.|
Oversized alternatives. Lift absolutely needed. When going for these sizes, expect also to do some serious bumper manicure (trimming or completely replacing). Not only are these diameters too large to fit without major adjustments, also widths larger than 267 mm (10.5 inch) will seriously rub car parts (fenders) and also protrude outside of the car body, which is illegal in many countries.
Furthermore, engine performance and braking effectivity will significantly deteriorate. Expect therefore to change gear ratios, and to upgrade brakes to heavy duty substitutes. Additional alterations required include the obvious body lift, spare wheel carrier adjustment, bumper manicure, etc. And expect to often replace broken half-shafts, drive shafts, hub assemblies and diffs. Finally there is a higher pliable tyre sidewall, increasing the left-right tilting potential of the DSII. Retaining sway bars, and ACE is reported to have sufficient good (on-road) stabilizing effect. Interestingly, fuel consumption has been reported to be not increased for these tyresizes, but contrarily seems to be stable or even better.
Overall, these oversized tyres, are only for the brave of heart, but necessarily in combination with a substantial body lift, you get an enormous under-diff clearance! Not many reports that people have actually fit these sizes, though.
The people wishing to fit these tyres are the more adventerous types, so won't fit road-biased ones. In this size, many very potent, and therefore attractive tyres come available, such as Simex Extreme Trekkers, Interco Super Swampers, and numerous big MTs of various makes. It is also estimated that off-road capabilities of wheels already increase with merely size, so that even All-Terrain tyres in 33 inch tyre size will provide enhanced off-road performance.
Standard tyre sizes are given in the metric form WWW/PP-RR where WWW represents width in mm, PP represents profile in % of the width, and RR represents wheel (just the metal rim) diameter, always in inches. It defaults to the stock 235/70R16 tyre size. Pressing the 'Go US' button converts this format to the US tyre size format, and gives comparison data against the stock tyre size.
Alternatively you can enter an US format tyre size, of the form DDxWWxRR, where DD is the tyre diameter, WW the the tyre width, and RR the rim diameter, all in inches. This tyre defaults to 30x9.00x16, which is an empirical size close to the stock 235/70R16. For the comparison, the stock metric size of 235/70R16 is used.
Alternative tyres sizes can be calculated with the WheelSizeCalculator Excel spreadsheet
With special thanks to Sean Butler-Lee for the the calculations form, to Bryan McGlade for the WheelsizeCalculator spreadsheet, and to Greg Bright, Greg Hren, Greg Davis and Simon Lun for the sound advice with respect to 33 inch or larger, oversized tyres on a DSII (don't).
This Howto is maintained by Wim van Dorst. Last update: 26 December 2004
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