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Sadly, my wonderful electra cruiser got stolen on tuesday. I am a college student with no other transportation, i need a new bike RIGHT away, the busses in my town are currently on strike and not running, so im looking for a cruiser around 120$. Im 5'7 300 pounds (yikes!)

Before, i kept getting 4 flats a week. I already determined the cause in my previous question, it was that, in short, i need a higher air pressure. The tires i had (that were stolen with the bike) were 26 x 2.125 and read on the side wall that they can hold 45-65 PSI of air.

Walmart has cheap cruisers. So today i went to walmart and saw:

  • Most cruisers there had 26 x 1.25 tires, much thinner than mine. Only a few had 26 x 2.125..... (Which is what i thought was standard for cruisers)

  • They all said on the sidewall the "tire can only hold 40 PSI of air"

Why is it that, a tire the exact same size as mine, would hold much less air than mine? And if i bought one and kept the air at 40 psi as it says, wouldnt it feel just like my old bike did at 40 psi (harder to ride, meaning more difficult to pedal) and have the flat issue all over again?? Huffy cruisers usually match the tires to the bike... So it would not be ideal to simply buy new tires.

There is another bike on craigslist im looking at. Its a genesis cruiser, big bike, with 29" tires. The reviews all say its ideal for bigger people... However yet again, the tires are only 1.25" wide... (I thought heavier people need wider tires?) And again, they only hold 40 psi of air (Ugh!)

In conclusion, i am asking the following:

  1. Why would the same size tire have different air limitations?

(The bike(s) im looking to buy, the tires say "fill tire to 40 psi" when normally, it would say "40 PSI - 65 PSI". All the tires say this no matter the size)

  1. since tires usually say "40-60 psi" rather than just one number, could these tires say just one number (40 psi) because thats a good median, meaning i could get away with 50-60 psi?

  2. If i can not afford new tires in addition to a nee bike, would you reccomend i stay away from these bikes with tires that can only hold 40 psi?

  3. Say i were to purchase the genesis, which has 29"x1.25" tires that say they can only hold 40 PSI.

    • I heard bigger people need wider tires (like 2.1" and up) and more air pressure. Would the fact that these are bigger, 29" tires make up for the fact that they are thinner and hold less air in terms of an easy ride?

    • Could i change the 29" x 1.25 tires for 29" 2.125 tires with out changin the rims?

  4. Any suggestions for where i can purchase an inexpensive beach cruiser style bike that doesnt have this tire issue?

closed as too broad by Móż, andy256, Gary.Ray Aug 26 '15 at 19:17

Please edit the question to limit it to a specific problem with enough detail to identify an adequate answer. Avoid asking multiple distinct questions at once. See the How to Ask page for help clarifying this question. If this question can be reworded to fit the rules in the help center, please edit the question.

  • Your bike was stolen, sorry. But still the same question. – paparazzo Aug 21 '15 at 5:22
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  • Um, no, its not AT ALL in any way shape or form the same question. Please read. Here im asking "why do the same size tires saythey hold different amounts of air" and before i was asking "why do i keep getting flats?" Those are two complete different questions, pal. – rogue Aug 21 '15 at 6:06
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    The air pressure a tire can safely retain is a function of both the geometry (width) of the tire and the quality of construction. I'm guessing that the Walmart tires are of poor quality. That said, most tires can safely withstand about 20% over their sidewall "limit" (though this depends to a degree on the quality of the wheel rim). – Daniel R Hicks Aug 21 '15 at 12:18
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    Welcome to Bicycles SE. To avoid confusion, please try to keep your questions concise and on point. For example, the info about your bike getting stolen, the bus strike, and the fact that you're a college student are all irrelevant to your question. Also, please try to only ask one question at at time. In this case, you are asking at least five different questions, and one of those has subquestions. Try splitting them up into completely separate questions. You'll get much better answers that way. You'll also be less likely to be downvoted and/or flagged for mod intervention. – jimchristie Aug 21 '15 at 13:49
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The pressure you can put in a tyre depends on the tyre and the rim.

The tyre bead (the band that stops it popping off the rim) varies from tyre to tyre, and some will not withstand as much pressure as others. An expensive tyre with a kevlar bead should be fine up to 120psi. The volume of the tyre is a factor too, but even a quality large volume MTB tyre would be capable of holding 80+psi. The tyre threadcount is also potentially a factor - this is basically a measure of how durable and robust the tyre is.

The wheel rim is obviously also important, as it needs to be capable of withstanding the pressure too. Weaker / cheap rims will not withstand the same pressure as a more expensive rim.

I'm guessing the bikes you're looking at have tyres only designed to hold a lower pressure due to the bead and lower threadcount.

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    I believe you about the rim. But how come we never see (or I have never seen) maximum tire pressures printed on the rim? If you took high quality road tires and inflated them to 160 PSI on a cheap Walmart road bike, what would happen? Would there be a reasonable probability that the rim would explode? – Kibbee Aug 21 '15 at 12:54
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Ok there are a number of questions in there.

1) 29" vs 26": that's not a question of which would hold your weight better or worse. 29" rolls a bit better, especially over rough ground, so if that's important to you, then go for 29". A bike with a very small frame for a short person, will work better with smaller wheels - i.e. 26" - but at 5'7" I reckon you'll be fine on either.

2) Wider tires, e.g. 2.5" vs 1.25", with the same amount of air pressure will make the ride firmer, and will hold more weight. E.g. if you put 40psi in a 2.5" tire, and 40psi in a 1.25" tire, then the wider one will feel harder when you're riding it, and will make it less likely that you squash the tire right down when you hit a bump - so you'll get fewer pinch flats.

Note that there is a maximum width tire that you can fit on your bike before it will start rubbing on the sides of your frame. This will not be printed anywhere so you have to figure it out by trying different sizes.

However, if you put more air pressure in the narrow tire then it will support you just as well. In that example you'd have to put double the pressure in the 1.25" tire because it's half as wide as the 2.5". So why don't you just put more air in the thinner tire? See below....

3) Why do different tires have different "limits" on them. That's a quality question. The pressure recommendation is usually written like this: "25 psi - 50 psi". What this means is that if the pressure is less than 25 psi, you'll almost certainly get pinch flats, and if the pressure is greater than 50 psi, then you risk blowing the tire off of the rim. Better quality tires have higher numbers at the high end: e.g. 25 psi - 70 psi. Some tires go as high as 140 psi, especially very narrow racing tires.

So given your concern about supporting your weight and not getting pinch flats, I would recommend:

  1. Stay with the 26" wheels if that is what your bike has now.
  2. Get the widest tires that will fit in your frame easily (e.g. 2.5").
  3. Go for a good quality tire, not the cheapest.

Good luck!

  • Thank you for your answer, you brought up good points i havent considered. However to clarify, the tires on the bike(s) im looking atsimply say "fill tire to 40 PSI" Not "40-65psi" or whatever, like most do. So, is that simply because the bikes must come with cheap tires, or is that just a "median" reccomendation? – rogue Aug 21 '15 at 6:08
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    That's hard to say… They could be low quality tires with very little room between pinch flats and bead failure. Or they could have a low opinion of their customers and figure they'd confuse you with a range. – dlu Aug 21 '15 at 6:31
  • Haha! Im honestly hoping its that... I need a bike and literally every "low budget" one i can find (even the schwinns) the tires say they only hold 40 psi. Its driving me crazy because i like a rock hard tire. Makes for an easier ride. – rogue Aug 21 '15 at 6:50
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    @rogue - Keep in mind that most bike tires, especially those on cruiser-style bikes, are woefully under-inflated. If the tires say "Fill tire to 40 PSI" that's almost certainly the minimum pressure, and the tires can manage 65 PSI or so. The manufacturer is trying to emphasize at least getting the minimum pressure. (Likely if you look VERY CLOSELY you will find the pressure range on the tire, in fine print.) – Daniel R Hicks Aug 21 '15 at 12:23
  • Yes!!! Thank you! Thats EXACTLY what i wanted to know. I didnt think it was possible the tires were THAT horrible. – rogue Aug 21 '15 at 13:34

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