Thread: Larger Tyre Issues

The website below was posted in an earlier tyre thread but is helpful in pointing the way to warranty and sizing issues for the D3. If running 19", Goodyear have a G4 event tyre - (MT/R) that doesnt show on the OZ website but is available @ 255/55R19S with a load index 111.

NextStepDesigns Blog Archive LR3 wheel & tire specifications and options


regards, John

I've been told by my tyre dealer that the MTR 255/55R19's are no longer available (thank goodness I have 5 nearly-new ones). It seems that Goodyear are making a new design MTR with aramid fibre in them with a slightly different (side-specific?) tread. The 255/55R19's don't have the aramid and are not side-specific. My tyre dealer seems to think that since neither the G4 available nor the G4 Challenge being run, then Goodyear is no longer making the tyres for the D3/D4. Should be interesting for soon-to-be D4 owners as they can't go down a rim size. I bought a set of 18" wheels and AT tyres to preserve my MTRs for the next few years.

Originally Posted by chuck

Has anyone had any issues with fitting larger tyres to their D3 relating but not limited to the following;
1. warranty
2. traction control
3. dynamic stability control
4. fuel economy
5. fit

I am contemplating 265 x 70 x 17 - 31.6".

Thanks

Chuck

1. Warranty will depend on the claim in question. LR are within rights to refuse if the larger diameter was a cause.

2. Traction control is unaffected

3. Stability control is affected as the vehicle is travelling faster than the computers think it is. The question is whether it is sufficiently affected to be concerned. There is no definite answer unless you conduct some serious testing on a skidpan, but for the sort of diameter increases we're talking about for a D3 it is unlikely to be an issue.

4. Fuel economy will be affected more by construction (weight) and tread pattern. Expect to lose a little. This is often masked by other changes made at or around the same time as people fit their cars out.

5. The maximum diameter increase is somewhat limited on the D3. Not clear what can be run without rubbing, and you may not know what rubs and what does not without careful testing in all suspension modes, pushing the wheels to the bumpstops and at full lock for the fronts. I have heard of one D3 that had "no clearance issues" till it hit a bump at speed...

Consider your state's roadworthy laws too.

Be careful on using web-based tyre size calculators. Last night I changed over from Cooper HT+ 265/60R18 to Goodyear MTRs 255/55R19's (going out for some mud this weekend). Side-by-side the two tyres are within 1mm of being the same diameter (each tyre has about 3k on it, so wear is not a factor). The internet calculator I use shows that the HT+ should be 12.1mm bigger in diameter than an MTR.

Since the MTR is original equipment for a D3, the Queenslanders may be able to argue that bigger tyres are within size spec after all.

After I fitted Cooper S/T's, fuel consumption increased by at least 2 litres per 100 klms....urban peak period driving, but about 1 litre per 100 klms freeway/country driving. I am in no doubt that the tyres make the difference over OEM Wranglers.