13" rim tyre sizes.

[Ronno]

Hi, I am looking at getting a set of new tyres for my FC sedan restoration project, I am going for the mostly original look and from other posts, I see that the radial equivalent size is 185/70 R13? I have heard that here in WA you are allowed one size up so maybe 185/75 would be ok? (if I can find them as I believe it is a difficult size to source). In my opinion, maybe that size would also look better as I always thought the original tyres and rims looked a little small but maybe that is part of the appeal, would they also be the highest legal profile without causing fouling issues. My other question is do I fit tubes or can I enlarge the valve hole to except the tubeless valve.   Thanks Ron.

[Ronno]

Maybe I should have also added a higher profile would give me a better gear/speed ratio (in my opinion).

[Errol62]

I believe 185 are really too wide for a 4 1/2” rim Ron. The 175 13” Nankang light truck tyre are closer to the original 640 13 cross ply. They are taller than the 185/75.

As to the rims, 60 years old aren’t they? Brand new ROH 4 1/2 x 13” are available at around $100 a pop. You won’t have any issues, they accept the original hubcaps and with the hubcaps on, look identical. If you stick with original rims then tubes would be a good idea I reckon. Although tubeless valves could be fitted to the original rims, sometimes the beads don’t seal too well.

Just my 2c worth, as they say.
Cheers
Clay


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[Ronno]

So I have looked at another earlier post and 185/80r x13 is recommended a couple of times, I think that is the size I will go for. The tyre place/fitters should be able to advise me re; tube vs tubeless.

[Errol62]

Let us know what you find Ron.
Cheers
Clay


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[my8thholden]

Ronno..I will be running 175-70R13 tubeless rolling diameter compares to 6.40x13.( if tubes are not needed when fitting comes) with whitewalls on original standard Holden rims..The car came with those new tyres ,and a new set of rims ,Errol maybe has used different rims, and I have posted about this elsewhere on this forum..I didn't like the new rims ,so hunted around and got 5 original Holden rims, these other rims have stamped on the 3 hubcap fitting bosses , ROH on one ,Australia on one and 89 or 68 on the third .depending which way you look at it ..the fitting bosses have no lip to grip the hub cap ,someone put some weld on each to hold caps on ,the stud holes have no recess for the tapered end of wheel nut to fit ,and I have been warned they will crack between stud hole and centre hole..They may be cheap copies ,I don't know ,but i'm not using them when car is finished ,they are on it now with a mix old tyres only so I can move it around..Look carefully before you decide ..cheers Vern   

[my8thholden]

Ronno ..If you want to send me your mobile ,I will send you some close ups of ROH rims what I described in earlier post. Vern .0405 703 413 .

[fastjbav6]

Ronno - I have 185/80 x 13 Maxxis on my FB sedan. I've tried other sizes that come close but the steering, handling and acceleration doesn't quite feel right.
Unless you've driven with original size tyres you properly wouldn't be any wiser on what you're missing out on.

Regards seb

[Errol62]

ROH aren’t cheap copies. They are OEM supply LC Torana on.

I forgot to mention that you must use the later wheel nuts, LC - LX and HT - WB. Otherwise as Vern says, the wheel centres are likely to crack.

I measured a Firestone 6.50 13 cross ply I have hear at 610mm. Then measured a 175 70 13 at 560mm. The car will look like a roller skate with those tyres Vern and you will need to run a 3.55 diff in place of the 3.89 original, just to get the speedo to read correctly and get the same gearing as original.

The Nangkang 175x13” light truck tyres retail about $95 each. Reports are that the ride and handling with these tyres is fair.

Just saying.
Cheers
Clay


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[KFH]

I run Maxxis 185/80 radials on the standard rim, no tubes, without any problems.  To correct the speedo reading I use the gear from an FJ gearbox.  I think it is 22 teeth however a search on the forum will give the correct answer as the topic has been discussed several times.

Keith

[my8thholden]

Clay ..I hear you ..so the new rims that came with the car are Torana ..hub caps must be different cause the FC don't fit ,to be precise don't stay on ..there is no lip on the three lugs to hold cap on ,any way I wont be using them ,when the project is finished I will offer them to Torans boys ,I have 5 original 4.5J x 13 Holden rims and that's the way I am going ..
Spoke to my tyre man just now ,he said 175-70R13 is correct ,he doesn't recommend but if I want to he would accept fitting 185-70R13 , my call..
Not the Nankang  light truck ,his words ,''if they are 8 ply, ride and steering would be shit " ..I am just passing on what I am told ,no judgement here .all the best Vern ..

[Errol62]

No worries Vern. I would get the tallest tyres you can, realising anything taller than 70 is rare these days. Tyre guys are generally used to selling tyres to haundai drivers.
Cheers
Clay


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[Ronno]

Thank you all, it is good to hear varying opinions /ideas. I have a poor education and have an income to match so I will stick to the original rims. The idea of the light truck tyre is interesting as I think they would resemble the original conventionals but would like the originals sacrifice the ride quality? safety would be a consideration here, the ride is not as important to me as the car would not see a lot of use. The roller skate look worries me and the longer legs it has the better, less work for an old motor but maybe a killer on the hills? Love the white wall look- your car looks fantastic Keith. The Fe-Fc is a great Australian icon but I guess we are biased? I have a full restoration and a lot of work ahead of me but rather than try and move it about with old leaky tyres thought I would sort them out early on. Thanks Ron.

[Errol62]

Ron
A lot of sitting around will eventually put flat spots in your nice new tyres. I would be using the cheapest thing you can find that holds air. Im blessed with the luxury of having a zillion wheels lying around. I can’t let go of anything I think I might possibly use one day.
Cheers
Clay


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[RET]

Vern,

185/80R13 is the way to go. The driveline in my car is absolutely stock. I switched my TomTom Satnav to show miles per hour and tested the speedo against it, and it's as close as dammit. (Closer than the same test done on our other more modern cars, actually!)

I would counsel against 70 profile tyres. The difference in rolling circumference (according to this site) is

185/80R13: 1966mm or 820 revolutions/mile
175/70R13: 1862mm or 866 rev/mile

... it's about a 5.5% difference.

[my8thholden]

Thanks RET ..That really is food for thought  .I will certainly put that to the men at Tyrepower ..However you have compared a radial with a radial ,have you got figures for bias ply 6.40 X 13 that the car design is based on, under the same test ? , ..The relationship of side wall to tread width has changed and I wonder what such a comparison would reveal ..Vern .

[Errol62]

I measured an old 6.50 cross ply wheel at 610mm which just happens to be 24”.  Multiplying by Pi gives a circumference of 1916mm. 840 revs per mile (1609344mm) if you like.
Cheers
Clay


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[my8thholden]

That 840 not equivalent to either , however closer to 820 than 866 revs/ mile ..HMMM!!!

[KFH]

I forgot to mention that with the 185/80 and the standard diff the speedo was spot on.  When I put a 3.55 diff in the FJ speedo gear corrected it

Keith

[Errol62]

These days new cars all read at least 5% fast from factory, and up to 10%. Speedo gears have around 19 to 24 teeth so +/- 4 or 5% is the tolerance you can expect.


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