The OEM 18s in the picture won't clear the Brembos, I'm afraid. Disco/LR3 and Sport share the same wheel arches, hubs, etc., only difference is the front brakes in the S/C version which "disqualifies" any 18" stockers, whether from a Disco3 or a Sport.

As far as tire sizes, I have been running a 285/60R18 all terrain setup on an off for several months now (on my non-Supercharged Sport), and the only things that aren't accurate are the "slower" speedo and "pessimistic" trip computer / mpg calculator (and slow odometer, but that's a good thing!), meaning that when the speedo says I am going 60 mph, I am really going 65 mph. No big deal, though. The satnav's speed sensor is independent and self-calibrating. The advantage of a chunky tire like that is about an extra 1.5" of clearance off road over the stock setup, plus a magic carpet ride on the road, all that extra sidewall and rubber really make the ride extremely smooth and surprisingly quiet, despite the more aggressive tread - handling won't be as sharp, of course. Under full compression there is very slight rubbing on the rear wheel well, but it is really minor, and the only signs of it is a small square of worn plastic liner inside the rear wheel well. Like Drevs said, I wouldn't try to fit anything larger though, a 285/60R18 is about 31.5" in diameter and that's probably as much as you can get away with on Sport and Disco3. Some members on a different forum tried a BFG 275/65 in 18" and said it rubbed pretty bad on a Disco3. 

Another problem with running 18's on the S/C will be the speed rating....................... are the 18's suitable for the speed that the S/C can achieve. I would imagine that insurance companies would not be very happy should you have an accident in an S/C running on 18" tyres as the car isn't designed to run on them.
I believe that the S/C is fitted with a speed limiter because tyre technology for the sort of tyres that LR fit to permit offroad use is not up to the high speeds that an S/C can get to when it is unlimited. A Carbon Footprint is the mark a lump of coal makes when it's dropped on the ground.

Tata TDv8 HSE - Stornoway/ebony and straight grain walnut with towpack, Tasmods and an HST grille. Coming soon LEDs in the headlights
Staying - Epsom Green Defender 90 for playing off road

Hi Guys... Thanks for participating in trying to finalise a solution..

On thing I thought I would let you know is that given the proximity of the inside of the rim to the actual caliper now (appro/ 5mm clearance), there is higher liklihood that you get small stones stuck between the rim and the Brembo caliper.. All I have seen so far is that lodged stones scratch the inside rim, which doesn't phase me at all truthfully...

The only thing I started worrying about is whether there was a chance that the caliper could "rip off" if a tough enough stone got stuck between the caliper & the rim.. To put my mind at ease, I'm constantly checking clearances of other car's caliper to rim distance, and my observations have shown that heaps of cars actually have only around a 5mm clearance. Including the 2005 Jeep Grand Cherokee Laredo... Other cars with small clerances include BMW 3 series with larger brake set-up and a heap of other cars I now look at specifically for that purpoose.. But like I said, the oone that gives me a bit of faith about running a 5mm clearance is the Jeep mentioned above, because it si designed to be an off road car..

I am exploring the idea of machining a slight concave groove into the inside of the rim where the "scraping" from stones happen the most... I wouldn't need mreo than about 1.5mm extra to substantially reduce the scraping I reckon.. Plus, I don't really want to grind the calipers to give me clerance, since I have too much respect for the Brembo name.. I don't really have any other logic..

I am waiting back on an engineer to give me the o.k. to machine a concave groove (about 10mm wide in total) 1.5 mm deep into the inside of the rim, and what it would do to the structural integrity of the rim.. I will post the info once recieved...


A few comments on the recent posts by both "umbertob", "Tim in Scotland" & "drevs".


"drevs"

You mentioned that you are considering going to a 20" agressive tyre. I went through the same mind games when I was deciding what to do. There were two reasons I went for the 18" option, hope these reasons help you decide:

1. SAND DRIVING: The main reason I needed smaller rims was to get onto the sand. Anyone with low profile tires (i.e. Conti 20" that come standard with the S/C) know very well that deflating them doesn't help at all. On sand, you need as much tyre profile as possibile, so the tires can "belly" out when de-pressurised. So the 55 profile is a lot better for me on the sand. I tried my set-up deflating the pressures first to 20psi, which was slightly too low (only because I felt like I would peel the tyre off the rim with the stupidity I was doing!), and 24psi worked just as good for the sand as 20psi, but I felt that the tire wall was adequately strong.

2. 18" RIMS ARE CHEAPER THAN 20" RIMS: The other main reason for needing a dedicated off-road set-up was because I know I will bash my rims around a fair bit off road, so even if I had a set-up with the same tire size, it would be beneficial Ithat I have one set of rims I can smash up off road, and one good set for the on-road "looking good" factor. When I considered getting a spare set of 20" rims to kill off road, the costs were a lot more substantial than a set of 18" rims I can bang up..

Hope that helps with your decision on rim size..

With regards to driving around with the blocks off, I would recomend you be careful, as I don't need to tell you how important brakes are to your general wellbeing Plus, LR freaked out when I asked them if I could take them off... That's why I would go through the exercise of having the alternative shape blocks made up, and do your testing on them. Since testing the car without the blocks alltogether isn't of much help if you accept the assumption that you wouldn't risk being out in the middle of nowhere if your brakes fail, I suggest get the blocks made up.. Only cost me $20 AUD per pair, and any custom auto machinest should be able to make them for you without too much hassel. I will post the dimensions of mine (new blocks) next time I take them off.

With regards to the aggressive mud terrain tyres, I feel your pain. I would like them too. My instructions to my wheel & tire guy was the following:

1. Try and keep the rolling diamater as close as possible to standard (726 I think)
2. Match the load / speed rating of the stock 20" Conti's

All he could come up with was the Cooper H/T Plus tires, and they are the best mob around for off roat wheels & tires (so they should know!). There was another Cooper tyre, slightly more aggressive tread geared SLIGHTLY more for mud, and the profile was 60 (as opposed to my 55's), but the rolling diamater was slightly larger, and he only had 3 in the country at the time I needed to go off road... I made the "executive descision" to go with mine, dispite the slightly higher profile of the alternative ones, only because the H/T Plus tread was more suited for sand, and the majority of my off roading is on sand. I choose to rely on the car's smarts to deal with mud etc. as the only difficulty I have had with the car off road is on sand...

If you are willing to go outside the above 2 criteria, you might SLIGHTLY increase your tire choice. I'm constantly looking at that too, so if you find anything let me know PLEASE...

Wow, I should write a book!! (just looked up at how much I wrote)

"umbertob"

Thanks for the info on running larger profile and how it affects the car's "smarts".. Can you let me know what Rolling Circumference the 285/60/18's are? I would be interested in that because that would slightly increase my tyre chouce given the criteria I set for my tyre/wheel guy when he was sourcing some tyres for me.. If tha't the only problems you have running larger RC tires, I would be happy to share those problems with you

"Tim in Scotland"

Yes you are corect, the S/C does have some type of speed limiter based on the tyre speed ratings, Top Gear proclaims that the tyres would burst if they didn't have the limiter. This ie=s exactly why I required my whee;/tyre guy to keep within the criteria mentioned in my reply to "drevs"... I would suggest that this be adhered to by anyone else also, or otherwise, don't go over 60km/hr with the off-road set-up and you should be safe... Not much fun like that though


TO RECAP INFO TO COME:

1. Dampner Block dimensions / weight (modified shape as opposed to standard block dimensions)
2. Advanti Photon 18" rims - Load rating
3. Advanti Photon 18" rims - Speed rating
4. Advanti Photon 18" rims - exact offset information (just in case there are other good looking rims available with the same offsets etc.)
5. Exact rolling circumference of "umbertob"'s 285/60R18 tyres
6. Any more possibile tyre configurations given my Advanti rim set-up (18x8), and the rolling circumference info to come from "umbertob"
7. Possibile solution to reduce "rim scraping" as explained above


Cheers guys, and I'm looking forward to solving the last of the issues above with everyone's help..

Thanks for all the info!

So lets see...

I am looking at running 20's simply because I already have them. I also already have a set of 22" street wheels/tires (285/35-22). That's my daily driver set. I want to, as you have, get a second set of dedicated offroad rubber.
There are a few reasons why having a set of 20" offroad tires/wheels makese sense for me:

-I still have my factory 20" wheels, so all I'd have to buy would be tires. Frankly, I don't care that the wheels are getting dinged up a bit offroad... but that's just me.
-The recent release of that Cooper LTZ that comes in a 20 and has a pretty aggressive tread pattern.

That said, I think 18's are better (obviously, and for the reasons you stated) for offroad stuff. So I'm interested in your progress. Unfortunately there are many downsides to getting 18's:

-I have to buy new wheels. So far, I've had no luck finding an Advanti dealer here in the US. I have a guy at discount tire looking into it, but nothing yet. The Chinese company that owns Advanti has not responded to my email either...
-I'd have to sell my 20" wheels and tires.
-I'd have to go through the "experimentation" of aftermarket 18" wheels (although you're pretty much pioneering it all for me(= )

About catching the rocks b/w the wheel and the caliper... I wouldn't even give it a second thought. Any rock that's small enough to fit in there is just going to get crushed. I think the idea of removing material from the wheel spokes is WAY more dangerous than the potential rock chip that you may create on your caliper.
Your caliper is held on by two steel bolts that are way bigger (and stronger) than the 5mm stone that might get caught b/w the spoke and caliper.
Frankly, machining a bigger groove is only going to increase the size of the stone that could get caught in there, and thus potentially do more damage.

Interestingly, your two "Tire Criteria" are not even on my radar. If I'm going to have a dedicated set of offroad wheels and tires, I want a no-compromise offroad tire on there.
I'm not worried about speed rating, I won't be going over 100mph with my offroad tires.
I'm not worried about rolling diameter, actually I want the BIGGEST tire I can possibly fit - better ground clearance and better traction. Who cares if my speedo is off!? It's better for resale value, anyways.
I don't even care about durometer or wear rating. These tires will see 2000 miles a year, tops.

Umberto's are 31.5" diameter. You can use any online tire size calculator to figure the actual dimensions.
I'd say that his 285/60-18 might be an ideal size for you. He seems happy with his choice, and that's about as much rubber as you can fit under a RRS without causing problems.

Lastly... How about some pics of the wheels on your truck!!

Drevs,

Thanks for the info & thoughts, it's really good to have someone to finally bounce ideas off on this topic..

A couple of things based on your comments.

I agree that if you have some 22" road wheels that it's a bit of a muck around to sell the stock 20"s, but for the reasons I said about sand driving I'm sure you would get the benefit (if you plan on doing sand driving that is)... I would try selling the stock 20"s on EBAY if I was you though, because I really think it's worth going the 18"s not just for sand, but for tyre wall purposes when you are climbing rocks... I really noticed the difference climbing some boulders the other day with the 18"s on, even though my 20"s did it fine at the same place about 4 weeks ago, it was just the peace of mind knowing the tyre walls are climbing and not the rims..

I can ask my wheel guy if there is some way that he could possibily have a set of Advanti Photon's re-directed to the US through someone over there? Let me know if you want me to run it by him. The rims cost me $215 a peice, so I didn't think it was too much of an ask.. (i.e. I was prepared to be hit harder)...

Regarding running the 20"s with bigger tyres: I am a procrastinator, so when I return from off roading, it generally takes me a couple of days to change the rims back over... So inevitably I get stuck running the 18" off roaders for a few days, so I need them to pretty much comply (speed / load ratings etc.)... That being said, I really SHOULD sell the Cooper H/T Plus' and go with a more aggressive tyre based on Umbertob's rolling diameter info so far.. I would suggest we both look into ALL the options together and list our options on the thread.. Agree?

So here goes with the photos & vids..!!

CLOSE-UP OF 18" AROUND THE BREMBOS


ON THE FERRY READY TO HIT THE SAND


ON THE SAND @ 24PSI - No problem stopping on almost ALL soft sand


SOME RELATIVELY TAME SAND TESTING
http://www.youtube.com/watch?v=g-9SLtJXlh8


Let me know what you guys think...

I find this calculator very useful:

http://www.miata.net/garage/tirecalc.html

So there, the diameter of a 285/60/18 is 31.5", circumference 98.8". Based on my experience, I would therefore suggest keeping it at or below that number to avoid rubbing. As you can see from the calculator, upsizing this much will make your speedo about 8% slower. When upsizing tyres on larger size rims (such as 20s), it was correctly pointed out elesewhere you should also keep an eye on the cross/offset width of the tyre, which is mounted on a much wider alloy wheel and therefore may start rubbing against the strut inside the wheel, rather than on the well itself, so circumference alone doesn't always guarantee a tyre will fit... 

Won't it also rub on the brake pipes which was an issue on early cars running OEM bigger wheels/tyres? A Carbon Footprint is the mark a lump of coal makes when it's dropped on the ground.

Tata TDv8 HSE - Stornoway/ebony and straight grain walnut with towpack, Tasmods and an HST grille. Coming soon LEDs in the headlights
Staying - Epsom Green Defender 90 for playing off road

umbertob wrote:

tyre

drevs wrote:

umbertob wrote:

tyre

I had no idea you were bilingual!

drevs wrote:

[
In all my searching, there are ZERO mud terrain style tires in 'low profile' 18" or 20" wheel sizes.

A bit off topic but this weekend I have fitted a set of new BFG MT's to my Defender90 to replace a set of extreme Mud tyres (peat bogs up here swallow Defenders for breakfast with aggresive tyres after it has rained, which is frequently!) that were 5 years old and remoulds but had only done 3000 miles but are a liablity onroad and braking efficiency is almost NIL on them in the wet!. I have been running on BFG AT's for onroad use with mdoerate to hard offroading but what a difference in noise with the MT's - I reckon they are actually QUIETER than the AT's I normally run on which is really good news as I will be driving 200 miles to Smarticus's offroad extarvaganza shaortly and will do the run on the MTs rather than the AT's. It's a pity that BFG don't make either tyre in a size to fit either D3/LR3 or RRS, I would buy a set like a shot if they did. If you have a Freelander though they do make 17 and 18" suitable for that! A Carbon Footprint is the mark a lump of coal makes when it's dropped on the ground.

Tata TDv8 HSE - Stornoway/ebony and straight grain walnut with towpack, Tasmods and an HST grille. Coming soon LEDs in the headlights
Staying - Epsom Green Defender 90 for playing off road

Ok guys, now I've been inspired...!!

I'm putting THESE TYRES on my truck:

Rim Size: 18" x 8" Advanti Photon (will powder coat them black)
Tyre Size: 285-60-18 (as recomended by "Umberto") as not causing unbareable problems with wheel wells etc.)
Tyre Brand: Nitto Dune Grappler DT http://www.discounttire.com/dtcs/findTireP...;tc=NITRH7

OR SEE HERE FOR PHOTO:



The reason I think these are the best for my applicaiton is they are really geared for sand / dune hopping (surface area), and the tread pattern is agressive enoiugh to hack the bit of mud work I will be doing in my Sport. I predominantly do sand work anyway... Being in OZ on the beach and all

I'm glad in one way that I got my set-up working and let everyone on this forum know how to do it, but on the other hand now that I have got more info from everyone I have to sell my Coopers now!!

Bitter sweet I suppose...

BTW, I am still waiting back on the dimensions of the Advanti Photons (Offset etc. info), and as soon as I get it I will post. My wheey guy is still waiting back from manufacturer...

Here's a MOCK-UP of what the Nitto Dune Grappler DT would look like... I just found the Sport photo on the net, at the right angle, and photoshopped the tyres onto the car.



Who's in??

Would a 19" wheel with Goodyear MTRs not suit?

The 19" MTR are not available here in the US... dunno about AU.

Sorry - I should have listed the Dune Grapplers. I wrote those off a bit ago because of some lukewarm reviews from my local tire place. However, they would be great for beaches and whatnot. You've probably got a winner for your specific terrain. Be sure to post some pics when you've got them mounted.
And do keep us posted on the Photon specs (not that I can even find them for sale here in the US...)

And they are extremely difficult to to get hold of in the UK too............... A Carbon Footprint is the mark a lump of coal makes when it's dropped on the ground.

Tata TDv8 HSE - Stornoway/ebony and straight grain walnut with towpack, Tasmods and an HST grille. Coming soon LEDs in the headlights
Staying - Epsom Green Defender 90 for playing off road