TR2/3/3A Disc Wheek Size for TR3/3A

[Chuck Murphy]

Can anyone explain the story of Disc Wheel Sizes for TR2/3/3A cars? Are they 4Jx15 or 4.5Jx15? They evidently were 4Jx15 at the start of TR2 production but changed to 4.5Jx15 at a later date. When did this change happen? 1. TRA Judging Manual says "Disc wheels upgraded from 4J to 4.5J at TS 1869"; 2. Piggott says the same; 3. Triumph Spare Parts Manual changes part number for "Disc Road wheel" only once at TS 13046 (but does not list wheel sizes); 4. Moss says change was at TS 13046 for (disc) Road Wheels (they say Wire Wheels stayed at 15x4 thru TR4). My TS15623 and TS37200 cars have 4Jx15 wheels, as do other peoples cars whom I have asked. One person has a TS17xxx car from new and it has 4Jx15 disc wheels. Why are there so many cars with 4Jx15 disc wheels if they were changed to 4.5Jx15 early in TR3/3A production? Chuck

 

[TomMull]

Hard to disagree with Piggott and I don't have the book with me to check but the 13406 number seems to be quite well accepted as the change point. I suppose there is a reasonable chance that some later (your 15623) cars might have come with 4 inch wheels but I think that the 4.5 were reinforced as well as widened and it doesn't seem reasonable that lots of the inferior wheels would have been used on later cars. It would seem very unlikely to me that your 37200 would have come with the narrow wheels.
Hopefully someone with some real knowledge will sot this out.
Tom

 

[Geo Hahn]

...Hopefully someone with some real knowledge will sot this out...

Until they come along, I'll add...

I assume you know (and I think I know) how to measure a rim -- it is, of course, not merely a matter of taking a ruler and seeing how wide the rim is.

Also (for that knowledgeable person): Is there a way to tell a 4J from 4.5J when there is a tire on the rim and the wheel is on the tire?

 

[TRMark]

Check a little ways down the page. https://www.jalopyjournal.com/forum...emade-hot-rod-shop-tools.185116/#post-2000292

 

[TomMull]

Until they come along, I'll add...

I assume you know (and I think I know) how to measure a rim -- it is, of course, not merely a matter of taking a ruler and seeing how wide the rim is.

Also (for that knowledgeable person): Is there a way to tell a 4J from 4.5J when there is a tire on the rim and the wheel is on the tire?

Still waiting but I'd assumed the question came from size stamping inside the tire. With the tire on, as far as I know, you can only approximate, as the inside lip is not accessible. However, measuring the outside of tire (i.e. with the caliper in Mark's link ) at the bead should give a close enough approximation to distinguish and 4 and 4.5.

Tom

 

[TR3driver]

I believe ol' Bill just blew it on that one (and TRA apparently copied it from Bill). The later omnibus version of the Piggott "Original TR" books has been updated to only say the wheels were strengthened at TS1869 and that "later" wheels were 4.5 instead of 4.0. He goes on to say that "these later wheels are now often found on sidescreen TRs", which implies to me that they were not originally fitted to TR2-3B at all.

I've not run original wheels for many years, but I checked a couple that were laying around handy, and they were both 4J. I've only ever owned one car before 13046, and it left me with the same wheels that it came with. I also don't believe they could have switched at 13046, because the spare tire compartment was so small. Even with the larger compartment at TS60000, another 1/2 inch in rim width would likely cause problems, IMO.

So, while I don't know if 302262 was really 4J or the SPC is wrong, I do not believe that TR3/A between 13046 and 60K had 4.5J wheels.

 

[TomMull]

So, while I don't know if 302262 was really 4J or the SPC is wrong, I do not believe that TR3/A between 13046 and 60K had 4.5J wheels.

Hard to disagree with Randall either and I suspect he is right here too. Certainly makes sense with the expanded tire compartment at 60k. However, The Triumph Spare Parts catalog, amendment 3, shows a part number change at 13406. Perhaps my assumption that the part number change was from 4j to 4.5j is incorrect.
Tom

 

[Chuck Murphy]

Thanks Randall for checking your available wheel sizes, and to everyone else who replied. My conclusions agree with Randall's. The people to whom I have talked that have wheels where they can check the rim size have 4Jx15 on their TR3 & 3A cars. This question came up at a Triumph Club meeting and I will pass these results on to the club members. Thanks, Chuck