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determining rim size without ER TRO number

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determining rim size without ER TRO number

Old 11-29-21, 04:52 AM
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determining rim size without ER TRO number

Hi all

sorry for this very random question but I don't know who else to ask. Figured you might have some ideas.

Have an old pram that needs new tires as they keep puncturing and slimming has not worked.

The tires that came from the manufacturers have very limited information on them - and importantly no ETRTO number.

Two front ones say "INNOVA 10 X 2 1A-2611-3 Inflate to 28P.S.I. (195kPa)(1.95BAR)" and the

Two back tires say "INNOVA 10 x 2 1A-2611-4-2 Inflate to 28P.S.I. (195kPa)(1.95BAR)"

I bought another 10x2 tire (as this is the only information I seem to have) but cannot get it over the rim. I have trawled the INNOVA website but they don't seem to have technical information on there either, I have emailed the manufacturer INNOVA in Taiwan for mm measurements and rim measurement but have not heard back from them. Took it to my local bikeshop but they were stumped. recommended sliming the tubes, which we did and it worked for a few weeks until it caused a massive explosive leak on the bus leaving behind a massive pool of green slime and us stranded with a puncture, again... Have tried to measure the rim diameter on the wheels but hard to be accurate as the hub obviously protrudes. The pram manufacturer wen bust a few years ago so don't sell replacements and hard to get hold of INNOVA tyres in Europe.

Was hoping someone on here may know more about tires than I do and might be able to advise on how I can figure out what tyres would fit and where I could get them?

Can of course apply some maths and work out that the diameter is from the circumference - but should that be the inside of the wheel (by the rim tape) or the outermost edge of the rim... Tires obviously have to sit beneath the rim edge so how much smaller to calculate?

would very much appreciate any advice people have. otherwise will have to abandon an otherwise perfectly fine vehicle and that just seems super wasteful!

thanks in advance for any and all advice!

and apologies for the slightly not bike related question

Last edited by rim; 11-29-21 at 05:03 AM.
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Old 11-29-21, 05:59 AM
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more info

So, I read up on sheldonbrown tire-sizing guide to try to get my head around this.according to the site most 10x2 tires have an ISO of 152mm.

But having done my best effort to measure the circumference at the bead seat and work out the diameter it seems to suggest a rim size of 156mm (with any obvious margin of error for measuring variation). which would explain why I could not fit the tire I got from the bike shop
over the rim...

so, now I think I am hunting for tires that are 10x2 and have a rim size of 156mm.... does that make sense? and do you think e.g. ("Lixada Upgrade 10 Inch Compatible with Xiaomi Mijia M365/Pro Electric Scooter Tire 10x2 Inflation Wheel Tyre Outer Tyre on Amazon") would fit? (sorry it won't let me post URL)

second question is the width of the tires. there is an obvious difference in the width of the front and back tires, though both say 10x2... how do I determine the right width? does it have anything to do with the last number in the product code as that seems to be the only difference? or do I just ignore it and hope for the best?

appreciate any advice!
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Old 11-29-21, 06:58 AM
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Is there any sort of rim tape covering the spoke ends? If so, try removing that (temporarily) and see if the tire goes on. And you've tried the other "tricks" to mounting tough tires, right? Centering the bead in the rim, etc? It sounds like you've done your homework, so please forgive me if that's obvious.
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Old 11-29-21, 09:23 AM
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Do you have the tires that were on that rim? They should have the ISO/ETRTO number or a bastardized ISO on them. On some tires it'll be the tiniest print embossed or stamped on them. Knowing that will at least let you know the BSD of the rim. I say bastardized because some will still put 700 x nn instead of the correct ISO of 622 x nn. I think I've seen 650B's done the same way.

If you flat often then are you figuring out why each time you flat? Don't just assume your flats are road punctures. Might be a spoke poking through, maybe snakebites from too low a pressure for the bumps you hit or bad habit you've developed when installing the tube.

For the width part of your rims ISO, just measuring the inside width of the rim at it's hooks will be close enough even if you just use a tape measure and convert to mm.

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Old 11-29-21, 10:10 AM
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There are still tires being made with lacking size info labeled on them. But far more tires just do a bad job at making said labels easy to see. Some will place the ISO/ETRTO on the bead where it is hidden when mounted and can rub down over time. Others have this info molded in the tread portion. Really sad placements.

My Sutherland's shows only one bead diameter (of 152mm) in the 10 inch tire size "family". I suspect you have a combination of rims on the big end of their tolerance (and/or rims with a shallow center well) and tires that are yet to stretch larger than their molded size.

The cost of a tire mold is pretty high and for there to be a need for a different sized mold to be made the company needs to have a market for the tires produced. I have never heard of any other 10" tire other than the 152mm one. But I have dealt with too many "properly labeled" rim/tire combos that were real difficult to mount and/or seat. Andy
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Old 11-29-21, 10:45 AM
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search 10x2 stroller tire



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Old 11-29-21, 10:55 AM
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What Andy said. It's hard to believe (though not impossible) that the makers of your tram would have used something other than ISO 152 wheels and tires, since they would be responsible to specing and stocking non-standard parts.

I suspect you @rim need to read up on fixing flats and changing tires. Repeated punctures in the same tire mean that you're missing something. You've landed in a good place for technique sharing.
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Old 11-30-21, 04:29 AM
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Thanks all. I agree that it is strange for the tire not to have ISO information but it doesn't. In fact, the replacement tire I bought doesn't either! I have found other 10x2 tires that are 156mm - mainly used for wheelchairs or electric scooters and mainly produced in Taiwan or China.

It may well be that the rim is on the larger size and the replacement tire has not yet stretched beyond its moulded size. With a tire of such small diameter there isn't much wriggle room. In fact, neither myself nor the bike shop could get even the tire on the rim - even using all the usual tricks like centring the bead and soapy water etc. Haven't tried the rim tape trick yet as the tire is just too far off going on.

I accept that I might have to improve my technique and always really welcome to learning new techniques. Certainly the wheels may not always be inflated to ideal PSI. But there are 4 wheels and they all puncture from time to time. The treads look pretty knackered and I'm constantly picking glass shards out of them. For the first 2 years punctures were not an issue. For the last 2 they were a constant problem and only got worse as time wore on.

Anyways, thank you all for your input. I will persevere with the tires I have and slime/tape protection to see if I can make it manageable for another 6 months. I will also brush up on my technique!
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