Ah, the age old question! What wheels and tires should I use! Turns out that there are hundreds of pages of forum discussion about this.
MY first principles (yours may vary!)
- get as much sidewall as possible while still keeping the overall tire diameter under 31" so as to avoid having to grind frame horns, cut the wheelwells, or do major modifications.
- Another reason to keep the tires at or near the 31" mark was to ensure that I could still use the full-size spare wheel storage space under the rear of the truck. There is a school of thought that says "pull the wheel from that location and hang it off the back of the vehicle to make it easier to access, and to improve your angel of departure. I've done this on prior vehicles and I have mixed feelings on that. Getting stuck in super deep mud and having to dig out space to drop your wheel is a real edge case compared to the 10,000 times you'll open the rear hatch. For now, I've chosen to keep the wheel in that spot. I may throw an additional spare on a roof rack for an expedition but that would be very temporary.
- The points above dictated that I move down to the smallest possible wheel size which in North America means 18" rims. In Australia apparently they can get down to 17" as they have different calipers.
- go with the narrowest tire possible. Contrary to myth and the general trend towards wide tires on overland trucks, wider tires are not better, particularly on the LR4 as that can incur rubbing in the wheel wells. When you need better flotation, the key is not wider tires, it's airing down to get a LONGER (not wider) contact patch. MacMackenney ran 235 width tires for his London to Capetown speed record in a Discovery II but he was probably also running 16" wheels. Taller, skinnier tires work well and weigh less. I didn't find a lot of the well-known tires being available though in the 245 range and ended up looking in the 265 range.
- Get the strongest tread and sidewall that I can without incurring a massive weight penalty.
- If possible, do the whole thing without spacers.
WHAT ARE ALL THESE CODES?
ISO standard tire metrics are not super simple. I started from the OEM tires and worked backwards to find a set of minimum capabilities, knowing that I was probably going to exceed them but hopefully not by so much that the tire became a liability (too much unsprung weight.)
The OEM Continentals were
Quick Wikipedia overview of the regular codes below:
Quick Wikipedia overviw of the Light Truck codes are here:
It helps to have a place to look at all the ratings in tables side by side. I've marked the ones in orange that show where the OEM tires sat. They were passenger class tires with an XL rating, meaning that they had 4 plies, and ran at 42psi max. They had a Service Description of 111V, meaning that they could carry 2,400 lb at a max of 149mph at 42 psi. You can see where the OEM tire sits in the chart below in orange.
My goal was to go for a Light Truck (LT) type tire which provides more like 8-10 plies and in some cases they also have 3 ply sidewalls which are of course a weak spot when off-roading. You can see the target ranges below in green. Note that I didn't care what the speed rating was really - it's a truck and it's usually loaded with gear so the speed rating is basically irrelevant.
REVIEWING ALL THE OPTIONS
I'm pretty OCD so I had to map out all the possible options first, before narrowing it down to the ones marked in green.
TIP: If you want to see more, make your window wider!
OPTIONS THAT I CONSIDERED
Work without issues: You can mount the wheel without grinding the frame horns or rubbing on the wheelwell. You can also install it underneat the truck normally.
Minor Changes: You may have a bit of rubbing, or may need to grind the frame horns or have rubbing only at full lock. Also you may have a harder time fitting the wheel under the truck in the spare compartment.
Major Work: The tires will require modifications to the wheelwell, grinding to the frame horns, and will not fit under the truck without deflating the tire and maybe removing the heat baffle. It still may not even fit after all that.
- Defender 2020 18" 5 spoke Style 5094 dark satin grey finish. Will these work on an LR4? No clue. They look great but they're also $900/wheel!
Should work without spacers or grinding
Compomotive +44 Offset
Evo Corse DakarZero
TuffAnt 18x8 Steelies
Require spacers - and may require caliper grinding
LR3 18” OEM wheels
Lucky 8 Steelies
Unknown if this would work
Defender 2020 18" 5 spoke Style 5094 dark satin grey finish - $850 each!
WHAT I ULTIMATELY DID
- LR3 18” wheels. This required 30mm spacers and minor caliper grinding on front brake!! If you don't want to do any grinding you may want to look at the Compomotives or others listed above.
- REMOVED THE STOCK: 255/55/19 (763x255mm) Continentals
- ADDED A NEW 265/60R18 Cooper Discoverer S/T MAXX = 30”
Overall I'm happy with the result of this decision for the following reasons:
- The tires are the same diameter as stock so it doesn't impact odometer and trip computer data
- That means that my full-size spare fits underneath the truck fully inflated without having to remove the heat baffle or deflate the tire.
- I gained 1/2" in sidewall from the 19s.
- I'm running bomber hybrid 10-ply E-rated tires that have already proven themselves in very difficult terrain
- These tires are a bit loud-ish. Not terrible but definitely a step louder than the original road tires that were on here to begin with.
- I also have a very-hard-to-troubleshoot vibration in the front left corner now that comes and goes depending on tire rotation and wheel balancing but that completely disappears if I swap entirely different wheels/tires on. Still troubleshooting that issue...