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-   -   Off Road 18"s (http://www.jeepgarage.org/f190/off-road-18-s-65577.html)

Barboots 09-17-2013 11:33 AM

Off Road 18"s
 
I've been making up a list of some of the "harder" 18" tyres for off road use. I realised it might be of use to others and started to add in a few of the tyres which probably were not my bag, but went some way towards making it a "complete" list. I started to lose interest and appreciate it isn't complete, however as far as the tougher / more agressive tyres are concerned it's bloody close ;)

Note the percentage change figures are circumfrential, not radius (height increase) or diameter. I might add this in tomorrow with some other stuff I've missed / skipped... or not! :D

265/60R18 Factory 18"s = Baseline
Pirelli Scorpion ATR - Construction Not Specified
BBridgestone D697 - LT Construction

265/65R18 = 3.42% Increase
BF Goodrich AT - LT Construction

285/60R18 = 3.39%
General Grabber AT2 - LT Construction
Bridgestone D697 - LT Construction
Cooper Zeon LTZ

275/65R18 = 5.39% Increase
Falken Wildpeak A/T - LT Construction
General Grabber AT2 - LT Construction
Cooper AT/3 - LT Construction
Cooper ST
Cooper STT - True 3 Ply Construction
Maxxis MT764 Big Horn
Federal Couragia (not on website, found on eBay!)

285/65R18 = 6.77% Increase
Falken Wildpeak A/T - LT Construction

275/70R18 = 8.95% Increase
Mickey Thompson ATZ
Mickey Thompson MTZ
Cooper ST
Cooper STT
Cooper ST Max

Some of the bigger stuff is going to be a problem in the spare wheel well, and may even require wheels with less offset in order to push the tyre away from the upper control arm joint, which seems pretty close on my inspection. Anyway, this is a work on progress... I just thought putting it here might spark things up a bit.

Steve

lt4vette 09-17-2013 06:22 PM

Re: Off Road 18"s
 
Quote:

Originally Posted by Barboots (Post 894973)
I've been making up a list of some of the "harder" 18" tyres for off road use. I realised it might be of use to others and started to add in a few of the tyres which probably were not my bag, but went some way towards making it a "complete" list. I started to lose interest and appreciate it isn't complete, however as far as the tougher / more agressive tyres are concerned it's bloody close ;)

Note the percentage change figures are circumfrential, not radius (height increase) or diameter. I might add this in tomorrow with some other stuff I've missed / skipped... or not! :D

265/60R18 Factory 18"s = Baseline
Pirelli Scorpion ATR - Construction Not Specified

265/65R18 = 3.42% Increase
BF Goodrich AT - LT Construction

285/60R18 = 3.39%
General Grabber AT2 - LT Construction
Bridgestone D697 - LT Construction
Cooper Zeon LTZ

275/65R18 = 5.39% Increase
Falken Wildpeak A/T - LT Construction
General Grabber AT2 - LT Construction
Cooper AT/3 - LT Construction
Cooper ST
Cooper STT - True 3 Ply Construction
Maxxis MT764 Big Horn
Federal Couragia (not on website, found on eBay!)

285/65R18 = 6.77% Increase
Falken Wildpeak A/T - LT Construction

275/70R18 = 8.95% Increase
Mickey Thompson ATZ
Mickey Thompson MTZ
Cooper ST
Cooper STT
Cooper ST Max

Some of the bigger stuff is going to be a problem in the spare wheel well, and may even require wheels with less offset in order to push the tyre away from the upper control arm joint, which seems pretty close on my inspection. Anyway, this is a work on progress... I just thought putting it here might spark things up a bit.

Steve

Thanks Steve - great info. I would add the Bridgestone D697 LT in the Baseline size of 265/60/18. It seems to be that these are the only LT construction in the OEM size, and a couple of the others on JG are using them.
Russell

noons 09-17-2013 10:01 PM

Re: Off Road 18"s
 
Nice work Steve!

Barboots 09-17-2013 11:31 PM

Re: Off Road 18"s
 
Quote:

Originally Posted by lt4vette (Post 895203)
Thanks Steve - great info. I would add the Bridgestone D697 LT in the Baseline size of 265/60/18. It seems to be that these are the only LT construction in the OEM size, and a couple of the others on JG are using them.
Russell

Thanks for picking up my oversight on that one Russell :)

Amended to reflect the Bridgies.

Cheers,
Steve

BobT 09-18-2013 07:58 AM

Re: Off Road 18"s
 
Good research Barboots! Regarding a wider tyre option, there is no doubt they look cool. However, from what I have read, they may actually be disadvantageous in sand. This is opposite to what one would expect. The wider tyre has to push a wider bow wave of sand. Old Land Rovers with their skinny tyres had little difficulty in sand. OK, we aren't talking about much but my point is that it is a mistake to opt for a wider tyre thinking they will perform better in sand. Opt for wider tyres for bling only.

BTW, I went for D697's for the very reason that It4vette states. They are the only LT tyre available in the OEM size.

Barboots 09-18-2013 08:48 AM

Re: Off Road 18"s
 
That certainly is the old story Bob, but the equipment has changed and we need to consider whether a "rule" or approach still applies.

The wider "wave" taxed the old asthmatic diesels terribly, but if you have the power to push it then it's less of a factor... eespecially if you can get more on top of it. Bear in mind it's mostly an issue as far as getting moving, as testified by all those smoking clutches! Also consider that the reduced gain in footprint from lower profile tyres could be offset by going that little bit wider.

The sand to the North of Perth is incredibly hungry, and I might have spent a thousand hours operating and directly observing almost every 4WD sold in Australia negotiating it. I agree... skinny high profile tyres with plenty of air out of them are best for for the old nags... but we've got ponies mate. :D

Anecdotally, I only noticed improvement when I ran 275's on my old Prado which came with 265's. That was going to a slightly harder carcass as well, which shouldn't help. It was a V6 petrol auto, so had reserve to push them.

I have no concerns about fitting wider than 265's in the context of sand driving. Clearance on the upper control arm ball joint is another matter, and may require an offset change. I'd rather not go that far again, though it's always tempting. :cool:

Cheers,
Steve

lt4vette 09-18-2013 05:25 PM

Re: Off Road 18"s
 
Does changing the offset to accommodate wider tyres (or for any other reason I guess), increase the load on the hubs or bearings enough to be a problem? Would it have warranty implications?
Thanks,
Russell

Barboots 09-18-2013 10:28 PM

Re: Off Road 18"s
 
Quote:

Originally Posted by lt4vette (Post 895848)
Does changing the offset to accommodate wider tyres (or for any other reason I guess), increase the load on the hubs or bearings enough to be a problem? Would it have warranty implications?
Thanks,
Russell

Yes Russell, the additional leverage can add to the load on the bearings. Whether this is significant given the huge inset of the standard wheels would be debatable. Currently they receive a massive leverage effect from the inside edge of the wheel, say if stepped up on a rock. Well that's my assessment of the situation anyway.

Anything seems to have warranty implications, however there needs to be a close association with the modification and any fault to have validity. If it was a bearing issue you'd probably be paying for it given Jeep's friendly nature.

I went from a -17 to a zero offset on my Prado. It has expensive "sealed for life" bearings and I had a slight concern that given the almost daily off-road use there would be a cost down the line. I've only done 70kkms since, but there's no hint of an issue.

I guess my last comment is that this time around these will be a second set of wheels for me, so the dealer will never see them :thumbsup:

Cheers,
Steve

lt4vette 09-18-2013 11:17 PM

Re: Off Road 18"s
 
Quote:

Originally Posted by Barboots (Post 895990)
Yes Russell, the additional leverage can add to the load on the bearings. Whether this is significant given the huge inset of the standard wheels would be debatable. Currently they receive a massive leverage effect from the inside edge of the wheel, say if stepped up on a rock. Well that's my assessment of the situation anyway.

Anything seems to have warranty implications, however there needs to be a close association with the modification and any fault to have validity. If it was a bearing issue you'd probably be paying for it given Jeep's friendly nature.

I went from a -17 to a zero offset on my Prado. It has expensive "sealed for life" bearings and I had a slight concern that given the almost daily off-road use there would be a cost down the line. I've only done 70kkms since, but there's no hint of an issue.

I guess my last comment is that this time around these will be a second set of wheels for me, so the dealer will never see them :thumbsup:

Cheers,
Steve

Thanks Steve,
Good points. If as you say most of the leverage is currently on the inside of the wheel, then for a small move in the offset to cause a problem, you'd have to assume that the bearings were quite asymmetrical in some way, which seems unlikely.
I get my Overland (ORAII) sometime in the next few days, and I have been trying to decide whether to try to trade the Khumo's immediately, run them bald then upgrade to an LT, or a second set of wheels and tyres for the rough trips. Like you, I have come down on the side of the second set of wheels. So I'll be looking for 18" wheels - which Jeep says should be OEM or else they may not be compatible with the TPMS! Know anything about that? Maybe the rim shape or something.
Thanks,
Russell

EDIT: I guess what I said about asymmetry is not really the case - they are obviously designed for load under cornering.

Barboots 09-18-2013 11:54 PM

Re: Off Road 18"s
 
Russell a key reason for the massive negative offset used today is to assist suspension design... I understand it is advantageous to have a longer pivot with independent systems, primarily with regard to scrubbing. I also believe it is beneficial for the design of the actual suspension dynamics.

Your edit is correct though... shifting the offset outwards does increase load during cornering. No argument there!

I'm struggling with the same concerns as you. No one seems to know whether the TPMS sensors will fit their Jeep specific aftermarket wheels! The market seems a void of intelligence, or give a sh!t factor at the least. Despite my wants, I'll probably go with an OEM Jeep wheel. That said I've got some -45 offset wheels on order "for a look"... the supplier is apparently OK to take them back. Do I buy 4x TPMS sensors online in anticipation of them working??? Probably, as any genuine 18"s I find without tyres will probably have had them stripped. That's my position... as of today :lol:

Why not buy 20"s for around town? There's a few about at the right price. If I were you, I'd sell the 18" tyres immediately... but everyone has a different angle to that!

Cheers,
Steve

lt4vette 09-19-2013 01:26 AM

Re: Off Road 18"s
 
Quote:

Originally Posted by Barboots (Post 896015)
Russell a key reason for the massive negative offset used today is to assist suspension design... I understand it is advantageous to have a longer pivot with independent systems, primarily with regard to scrubbing. I also believe it is beneficial for the design of the actual suspension dynamics.

Your edit is correct though... shifting the offset outwards does increase load during cornering. No argument there!

I'm struggling with the same concerns as you. No one seems to know whether the TPMS sensors will fit their Jeep specific aftermarket wheels! The market seems a void of intelligence, or give a sh!t factor at the least. Despite my wants, I'll probably go with an OEM Jeep wheel. That said I've got some -45 offset wheels on order "for a look"... the supplier is apparently OK to take them back. Do I buy 4x TPMS sensors online in anticipation of them working??? Probably, as any genuine 18"s I find without tyres will probably have had them stripped. That's my position... as of today :lol:

Why not buy 20"s for around town? There's a few about at the right price. If I were you, I'd sell the 18" tyres immediately... but everyone has a different angle to that!

Cheers,
Steve

Hi Steve,
Where I live, I just about need the height of the 18's just to drive on the rotten pot-holed roads. I have a Merc with 45 and 35 profile tyres, and have wrecked 3 rims (and $450 tyres!) in two years. So, even if I wasn't offroading, I would have gone for the 18's on the Jeep.
With the TPMS, probably the only way is to look at an OEM wheel with the tyre off, and the potential aftermarket, and try to compare them. The only thing I can think of is the width of the "ledge" the valve stem goes through, or the angle of it so the sensor doesn't get in the way during tyre removal. Jeep are VERY specific about how to remove and replace a tyre - so much so I'd be amazed if Bob Janes' followed the procedure.
Thanks, Russell

duggy2145 09-19-2013 03:41 AM

Re: Off Road 18"s
 
Just to add to the list,Cooper AT/3's are available in 265/65 18 which I am running on my WG.
Cheers Doug


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