Hi all, I just found this thread while trying to find out why an NTC7739 rim isn't suitable for conventional, metric rim fitting tyres, in this case the 235/70% r16s on my 1997 Discovery 300TDI.
The car came to me with only 4 original wheels with it, so I looked for something that matched the measurements of the standard, factory fitted JDM spec wheels that look similar to the NTC7739 of UK origin. Four of my selected tyres (Yokohama Geolandar GO15 in the correct 235/70%r16), which were fitted on the road wheels, are absolutely fine, but the fifth, mounted on a UK made but otherwise similar to the car's factory wheels, developed an egg in one sidewall after it had been sitting in the boot for six days. I returned to the tyre fitter, who ordered in another tyre of the same spec and the next day, I went to have the replacement tyre fitted on the spare wheel. The fitter wasn't doing anything wrong, but had had the decency to suggest that failures of these tyres were so rare that he was sure that it must have been down to a fitting error however, within milliseconds of the replacement tyre making the distinctive loud pop that said its bead had settled into the wheel, a massive escape of air happened and tyre number 2 had, this time as soon as it was fitted, failed in the way of the first. The fitter then ordered yet another and had, in the mean time asked the advice of a chap from the neighbouring business, a Land Rover specialist, who examined the wheel and declared it perfectly fine for use, but that the rim, instead of being intended for a conventional, metric size such as my car's 235/70%, was in fact designed for imperial wheels of a type that would have been intended for the larger, more serious off road oriented tyres whose size is measured across the OD of the tyre when fitted, such as the 35x10.15 - 16s that I once found fitted on another make & model of Japanese 4x4, owned for a very short time because the tyres and much of the rest of it were rubbish.
A couple of removed tyres of the same size as mine were then tried on the wheel and sure enough, they both broke their bead when reaching the pressure that should simply have set the bead into the wheel rim.
I've since found quite possibly the only other UK source of a fifth, correct wheel (as seen on JDM LR 50th anniversary models such as my own car) so am buying that, but has anyone else on this board (can't use search as I haven't had my membership approved yet. Sorry!) ever heard of such a thing? The tyre people are being incredibly patient and have ordered yet another tyre that will go on the rim I'm buying as it actually comes with a worn out tyre that is of the correct size, meaning that my Yokohama will fit.
I have definitely seen these wheels on standard cars, without suspension and / or chassis lifts, so would it be reasonable to assume that the wheel I ended up with was also available with a rim profile that would have been intended for a standard, 235/70% r16 tyre? If so, how would anyone be able to tell? I'm trying to return this wheel as it's not fit for the stated purpose (D1 1989-1998- 205/80% or 235/70%)
Thanks in advance.
JayeBee
I have looked on many car fora to see whether anyone has had the same issues with the tyres in my car's size, the NTC7739 wheel that doesn't like being fitted with metric tyres
