Hi all, I've finally (after 2 years) got the restore company to send me the original R wheels for, well, my original R model

I'm not going to fit them at this time, as I prefer the L wheel currently fitted. However, I have a question. The wheel measures just over 4 inches in width. So, what max tyre size could be fitted?

is it 135 taking into account that a tube is still required?

Cheers
Rob

I'm using the same wheels I believe, without tubes, with 145/70R12 rubber. I like the way it looks and the grip is honestly more than I want (I was hoping to break the rear loose more with the Abarth engine). No issues at all with holding air except one which had some bubbled rust along the inner lip surface, will be ok after some thorough sanding.

I found the pair of those I have, It had some stamping on the rim but I forgot to take a pic of it to try and define what they were off......

The wheels in your picture Rob are designed to have tubes fitted---they do not have the tubeless tyre bead holding ridge. Whilst people have got away with using tubeless tyres on this style of wheel, it cannot be recommended

There are two widths for that style of rim. All early 126s had the 4" width fitted with 135 tyres and generally the 500R had the 3.5" width & 125 tyres. I have a pair of the 126 ones that my pal took away to have sandblasted for me. They will be up for grabs when I get them back. There are also two different mounting bolt types. The standard 500 bolts with a spring washer and taper / countersunk 10mm ones more like the later 12mm 126 ones. Rims for the taper bolts are raised around the mounting holes.

the hobbler said:

Whilst people have got away with using tubeless tyres on this style of wheel, it cannot be recommended

Click to expand...

Tom, should I be concerned? I do believe mine are the same, but I did not use tubes. They've been great so far, but...

lazylobster said:

Hi all, I've finally (after 2 years) got the restore company to send me the original R wheels for, well, my original R model

I'm not going to fit them at this time, as I prefer the L wheel currently fitted. However, I have a question. The wheel measures just over 4 inches in width. So, what max tyre size could be fitted?

is it 135 taking into account that a tube is still required?

Cheers
Rob

Click to expand...

Hi Rob,

Afaik, the rim width is measured between the flanges, so it looks like your wheels are 3.5 inch wide - this would agree with what Toshi 975 says above, that the 500R used 3.5 inch width rims.

Going up one size in width e.g. from 125 to 135mm shouldn't cause any problems. There's generally 2 or even 3 widths of tyre suitable for each rim width - going with the widest tyre for a particular rim width is best for comfort, going with the narrowest is best for sharp handling (the difference is likely minimal). In the real world, your choice of tyre size may be limited by what is available nowadays.

I'm glad to hear that you plan on using inner tubes, just make sure that whichever tyres you select don't have little ribs inside (these look like little raised lines of rubber running from bead to bead) as these can chafe the tube resulting in deflation. (btdt)

If you however decide to forego the fitting of tubes (as many have done without any apparent problems), you might need to do something about the significant pitting on the rim bead seat, (visible in your 2nd picture in post#1), in order to avoid air leakage.

Tubeless tyres have an air-tight internal softer layer which is vulcanized in place and replaces the tube, this layer also covers the beads of the tyre to ensure a good seal. The tyre beads must fit tightly against the bead seats so there is a 5 degree taper to the bead seat and 'safety hump(s)' are employed as 'the hobbler' has pointed out above. (post#4)

Al.

Morning Al and you are quite correct, flange to flange is 3.5 inch.


I think if I ever do fit I will be either a 135 or a 145 tyre with a tube. I'd rather not take the risk of a tubeless tyre on a wheel that is not designed for it.

Anyway, its conjecture at the moment, as I'm happy with the L wheel fitted to Val. In future, if I get bored I may revert to these wheels for a period.

Thanks to all who commented.
Rob