Largest Functional Tire Without Mods

HT said:

Tried to get a short video but it wouldn’t upload… here’s a photo that might show the clearance (apologies in advance for my poor photography and dirty hands).

Click to expand...

Thanks HT! This helps a ton.

Ferrugenfish said:

Hello ladies,

Anyone know what the largest tire size is that can be used without rubbing, binding, and without cutting the vehicle to make it fit?

I'm also wondering if there are any options out there for upper control arm replacement to properly lift the truck say... 4 inches, while retaining correct angles.

Lastly... I see that spare tire upgrade size will likely be limited by the left rear access door needing room to open before the right side... looks like about 2 inches further would be the max...?

Click to expand...

The gap is 28mm with 265/70/r17 tyres that come stock

265/70 in standard on the 17 inch rim, if you want to wider but do not want to change the speedo reading or reduce clearance a 285/65/17 will give you the same height. 265 to 285 is 20mm wider tire. A 285/75 is a higher overall by 3 cm or 1.5 cm higher ride height.

HT said:

I ended up with 295/70/17 BFG’s. No lift needed. The little rear door only clears the spare by about 2 mm. I can say with relative certainty that that’s as big as you can go without spending some $$ on the spare wheel mount.

Click to expand...

I’m looking at this size tire as well with the Maxxis razr. However the diameter in that size is 33.5” and 12.17” wide. I’m fearful that even that little bit extra won’t clear the back door. The bfg in that size is 33.3 and 11.8” wide. That’s like 5mm larger. HT- what about clearances in the front lock to lock with the 295’s?

what are the stock wheel widths for the 17” alloy and Steelies?

Drausch1976 said:

what are the stock wheel widths for the 17” alloy and Steelies?

Click to expand...

7.5"

Drausch1976 said:

I’m looking at this size tire as well with the Maxxis razr. However the diameter in that size is 33.5” and 12.17” wide. I’m fearful that even that little bit extra won’t clear the back door. The bfg in that size is 33.3 and 11.8” wide. That’s like 5mm larger. HT- what about clearances in the front lock to lock with the 295’s?

Click to expand...

Hey mate,
Yeah I think you’re right to be concerned. Two reasons:
1. If the maxxis is .2 of an inch bigger diam, looking at my spare tyre, I really doubt there would be room for an extra 1/10 of an inch to open the rear door. That’s not the end of the world though- a few companies like black sheep are selling a mod for that issue.
2. The bigger problem might be up front on full lock (and compressing springs) you might start to touch the front firewall. Mine is close. So far, I haven’t noticed any contact, but I’m a fairly modest driver and I’m not doing difficult trails etc. Again not the end of the world - a lift would resolve that - and look awesome.

Thanks! May just opt for the 285/70 then. I may do the lift but not right away.

Drausch1976 said:

Thanks! May just opt for the 285/70 then. I may do the lift but not right away.

Click to expand...

Are you thinking about the Eibach lift? Are there other options right now?

Based on the Eibach website, it looks like they are offering a taller spring, but there aren't details on those springs, other than a 30 mm height increase. For example: (1) Is there a change to payload? (2) Do you need different shocks that are taller in height? (3) Are other modifications required?

30 mm = 1.18 inches, so maybe no other modifications are necessary. But this still seems like it would take the shocks out of the "normal" zone that they were designed to run in. In other words: when the vehicle is unloaded ("resting position"), the shocks were designed to be extended by X amount. If you lift the truck by 1.2 inches, the resting position of the shock has been extended, and is now X + 1.2 inches, so you probably lose "droop" - which refers to the downtravel of the shock. Shocks need both uptravel and downtravel when off road. Without a longer shock, this lift might reduce articulation. In the photo below, the front left tire is demonstrating "downtravel", or "droop". The greater the downtravel, the better able you are to keep a tire in contact with the ground.



I'm also curious about their testing, and how this lift affects driving dynamics (mostly because the control arms are short, and - even with a small lift - when control arms are short, the angle of those arms is changed more dramatically). With just a 1.2 inch lift, this may be a non-issue. I would guess that the lift has been kept to a modest 1.2 inches, because that is the most you can lift the truck before the length of the control arms becomes a problem. The short length of the control arms is a significant obstacle to lifting a vehicle, and it is something I have mentioned on this forum as evidence that Ineos did not engineer the vehicle in such a way that an owner might be able to easily modify the vehicle. Replacing short control arms with longer ones is a big deal, especially in a new vehicle. There are a lot of challenges, and lots of testing is needed. Even if they figure it out, it will cost $12,000-$15,000 to buy the kit (long arms, taller springs, taller shocks, other necessary hardware), and then most people will need someone to install it, because it requires cutting bracketry off of the frame, and welding new bracketry onto the frame (long arm kits are not bolt-on).

Eibach website:

stickshifter said:

Are you thinking about the Eibach lift? Are there other options right now? Based on the Eibach website, it looks like they are offering a taller spring, but there aren't details on those springs, other than a 30 mm height increase. For example: (1) Is there a change to payload? (2) Do you need different shocks that are taller in height? (3) Are other modifications required?

Click to expand...

No alteration of weight carrying capacity (unless you order their "for winch" spring and you don't have the OEM "with winch" springs), no change in shocks, no other mods required.

The assumption/presumption is that it is still well within limits based on Eibach also being the OEM spring manufacturer and Eibach's reputation for producing generally mild spring upgrades

anand said:

No alteration of weight carrying capacity (unless you order their "for winch" spring and you don't have the OEM "with winch" springs), no change in shocks, no other mods required.

The assumption/presumption is that it is still well within limits based on Eibach also being the OEM spring manufacturer and Eibach's reputation for producing generally mild spring upgrades

Click to expand...

Thanks Anand!

Any thoughts on loss of downtravel? If you gain ground clearance but lose some downtravel, there is a cost as well as a benefit to the lift.

Edit: Just found the forum thread on the Eibach lift - hadn't seen that before.

stickshifter said:

Any thoughts on loss of downtravel? If you gain ground clearance but lose some downtravel, there is a cost as well as a benefit to the lift.

Click to expand...

Could go the route of a home-brewed droop kit, like Safarigard offered for LR’s in the 1990’s. Seems like a good match.

stickshifter said:

Thanks Anand!

Any thoughts on loss of downtravel? If you gain ground clearance but lose some downtravel, there is a cost as well as a benefit to the lift.

Edit: Just found the forum thread on the Eibach lift - hadn't seen that before.

Click to expand...

Just a note:
If your reason for fitting these springs is, like globalgregors was thinking, to set the vehicle back closer to unloaded height when you are well loaded and travelling, then dampers and droop are all going to be happy and back in specified range.

We can all hope that the suspension was designed to perform well everywhere from unloaded to fully loaded, and I would hope they canvassed overloaded to some degree as well, so maybe with a mild change there is no need for concern? Offroading plus or minus 800kg is a broad range.

Tom109 said:

Could go the route of a home-brewed droop kit, like Safarigard offered for LR’s in the 1990’s. Seems like a good match.

Click to expand...

I was at the original Defender "Twist-Off" in Fruita in 1999, where Greg of Safari Gard was introducing his prototype 3-link front suspension. Sadly, the geometry had not been optimized and thefront axle "rolled" when doing a highway "swerve" test.....
Just shows that unless there is solid engineering and simulation of dynamic forces, modifying a vehicles suspension geometry can be a risky business.

James said:

Just a note:
If your reason for fitting these springs is, like globalgregors was thinking, to set the vehicle back closer to unloaded height when you are well loaded and travelling, then dampers and droop are all going to be happy and back in specified range.

We can all hope that the suspension was designed to perform well everywhere from unloaded to fully loaded, and I would hope they canvassed overloaded to some degree as well, so maybe with a mild change there is no need for concern? Offroading plus or minus 800kg is a broad range.

Click to expand...

Yes, correct - not just ride height but also the related idea that this gives the springs a bit more to work with over high-speed corrugations.

James said:

Just a note:
If your reason for fitting these springs is, like globalgregors was thinking, to set the vehicle back closer to unloaded height when you are well loaded and travelling, then dampers and droop are all going to be happy and back in specified range.

We can all hope that the suspension was designed to perform well everywhere from unloaded to fully loaded, and I would hope they canvassed overloaded to some degree as well, so maybe with a mild change there is no need for concern? Offroading plus or minus 800kg is a broad range.

Click to expand...

My main reason for going with these springs would be to lift the chassis so as to (1) gain some ground clearance for the very low-hanging fuel tank, as well as some other parts of the undercarriage, and (2) fit a taller tire with confidence that it will not rub on anything; the taller tire will, in turn, provide additional ground clearance under the differentials.

I have a lot of experience driving the trails around where I live in the Rocky Mountains. I know exactly what a solid-axle vehicle of this size on 31.6 inch tires can - and cannot - run without damage. The Grenadier, in stock form, does not give me access to a bunch of climbing and hiking trailheads that I regularly visit.

I would never take a stock Grenadier on a grade 7 trail (using the OnX grading system), and grade 6 trails would involve a fair amount of abuse to the rather thin skid plate that protects the fuel tank. I spent a good amount of time underneath the Trialmaster at my local dealer, and the fuel tank skid-plate is beat to crap, the rear diff has taken a few hits, and the rear skid has also taken a few hits. This damage was sustained on grade 6 trails. It is also worth noting that there is a lot of rust everywhere that has seen rock damage (except the rear skid-plate, which is aluminum). So if you are hitting your under-body skid-plates, you need to stay on top of the paint (a simple rattle can does the trick).

A 1.5 inch lift and the ability to run a true 33-inch tire - while maintaining full suspension articulation - will allow me to comfortably run trails graded 1-6, and I'll be able to run grade 7 trails with the occasional hit to the skid-plates.

Fitted today 33” 295/70R17 KM3

Caveman said:

Fitted today 33” 295/70R17 KM3

Click to expand...

Nice! DaBull

How’s the small door when opening?

The rear door has heaps of clearance.