| [ Total Views: 935 | Total Replies: 6 | Thread Id: 90613 ] |
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 beachbuggy61
Seriously Crusin Dubber
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| posted on May 24th, 2011 at 09:35 AM |
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Wheel sizes
Good morning all,
I've been told by the local constabulary that the wheels on my baja are too big! I have to return the wheel size to no greater than 15mm larger
overall diameter than original, which apparently is the law (haven't checked the RTA website yet tho).
Can anybody please tell me what the original tyre size would be for a '68? I've never had original tyres on it so have no real idea. I know they
were 15" rims but I want to be able to make sure that when I get new tyres fitted, they match the overall diameter numbers.
Many thanks,
Marc.
Baja
1915cc's of raw power 
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"The Lord does not subtract from the life of a man, the hours spent on his Volkswagen" Anon. |
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BRUTUS
A.k.a.: et tu, Brute
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| posted on May 24th, 2011 at 02:42 PM |
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Original wheels should have been 4J x 15", with 5.60 X-plys. If these were 80profile? (not sure for Xplys, thought some were 78?), diam. would be
24.0" or 609mm.
The metric equivalent today is probably 145 x 15, which for standard 80profile radials would be 24.1" or 613mm OD.
You could probably argue that those old 5.60 Xplys were superseded by 6.00 x 15: OD= 24.6" or 625mm.
The metric equivalent should be 155 x 15: OD= 24.8" or 629mm.
Similarly today 155 would probably be replaced by 165R 15, with OD 645mm or 25.4" (for 80profile). So you may be able to argue your way up to 645mm
from 609mm, as both 145 and 155 are probably "discontinued" (by almost all makers).
The biggest specified diam. I can see in a published document for 165R15 is 26.00", ie. 660mm.
{You may even be able to argue that "original wheels" also includes 4.5" x 15" (if they are 4-stud)...? And to push it even further, 175 radials
may have been allowed fitment on them...?}
You can easily calculate theoretical tyre OD as follows [example for 165mm x 15"]:
(0.80 x 165 x 2) + (15" x 25.4) = 645mm.
where 0.80 is the tyre profile (80% = 0.8), 165 is the width (mm), and 15 is the rim diam. (inch).
[Real tyres may vary by a mm or so from this.]
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psimitar
Son of Jim - Creator of Good
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| posted on May 24th, 2011 at 03:06 PM |
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In Oz you can't get 145 or 155x15 tyres at 80 profile so 165/80 is the best you can do. Every Beetle owner will have this dilemma in Oz.
For QLD only 15mm in tyre diameter is allowed from the largest tyre fitted to that vehicle. I think later GT beetles had 175/70's fitted and you may
be able to swing that one as it is the largest tyre fitted as a manufacturers option due to the beetle not changing in design by much after going to
BJ suspension.
So there ya go. Heres qld mods page
QLD
Mods
and NAtional code of practice pagesNCP
pages
Unfortunately a Baja would rarely fit in the confines of these rules so maybe your only option is to transport the tyres to where you go off road and
then pop the std size wheels on to go home. Even an engineer should NOT approve outside of these rules and so the rossers are in the right 
madness is in the eye of the beholder  |
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Aussie Dubbin
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| posted on May 24th, 2011 at 03:52 PM |
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Going back a way weren't early beetle fitted with a 16" somewhere back there? Theres one option.
Also weren't GTs fitted with 6" wide wheels...?
At that rate couldn't you argue to legally fit 17x7 or something to that effect... Wasnt there some rule about not changing the track by x amount...
As for the rolling diamater of the wheel. Is it a braking issue? Could you install type 3 rear drums to compensate for bigger wheels and tyres?
Anyway i dont have any reserarch on the topic so good luck. Just what ive heard over time.
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psimitar
Son of Jim - Creator of Good
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| posted on May 25th, 2011 at 03:40 AM |
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| Quote: | Originally
posted by Aussie Dubbin
Going back a way weren't early beetle fitted with a 16" somewhere back there? Theres one option.
Also weren't GTs fitted with 6" wide wheels...?
At that rate couldn't you argue to legally fit 17x7 or something to that effect... Wasnt there some rule about not changing the track by x amount...
As for the rolling diamater of the wheel. Is it a braking issue? Could you install type 3 rear drums to compensate for bigger wheels and tyres?
Anyway i dont have any reserarch on the topic so good luck. Just what ive heard over time.
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its the overall diameter of the tyre they'll call you on. Pre-50's did have 16's but you'd be hard pushed to utilise that in your case where as
the 5.5J GT wheels would be easy for the width of the tyre used.
They say it affects handling, braking etc due to the increased centre of gravity and rolling resistance/inertia. It's a legitimate reason cos if you
see those twat chromed wheels on the Hummer H2 at 22 inches they will handle and brake worse than the original would BUT you would only notice when
pushing the vehicle in a corner etc 
madness is in the eye of the beholder |
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beachbuggy61
Seriously Crusin Dubber
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| posted on May 25th, 2011 at 08:22 AM |
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Thanks for the input guys.
After I made the post (I always ask here first!) I did some reserach on various rolling diameters and came up with numbers around the 628.5mm so that
seems to be in the ballpark of your comments, Brutus. I've decided on some 205/60-15's which are well within the overall diameter numbers and
according to the guy at the tyre shop, who is also the Blue Slip guy, they will be legal.
Thanks for the help!
Cheers,
Marc.
Baja
1915cc's of raw power
Turbocharger
Intercooler
EFI
Crank fired Ignition
Runs E85
Engineered
"The Lord does not subtract from the life of a man, the hours spent on his Volkswagen" Anon. |
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Joel
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Now containing 100% E-Wang
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| posted on May 25th, 2011 at 10:25 AM |
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| Quote: | Originally
posted by Aussie Dubbin
Going back a way weren't early beetle fitted with a 16" somewhere back there? Theres one option.
Also weren't GTs fitted with 6" wide wheels...?
At that rate couldn't you argue to legally fit 17x7 or something to that effect... Wasnt there some rule about not changing the track by x amount...
As for the rolling diamater of the wheel. Is it a braking issue? Could you install type 3 rear drums to compensate for bigger wheels and tyres?
Anyway i dont have any reserarch on the topic so good luck. Just what ive heard over time.
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The 16" bug rims were long before they were sold in Aus, it was split window bugs that ran them.
The Lemmertz GT (sports rims) is a grey area.
Reason being they weren't actually wider, all the bugs that came from the factory with them (Euro GT, US fuel injected etc) were only 4.5" wide same
width as stock.
THe only exception bug that ever had the 5.5" Lemmertz GTs was the US Sports bug and they only had 165 tyres on them..
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