Much difference between 28,30 & 32 tyres???

[daninplymouth]

Hi, running farsports 50mm rims 24/30 int ext. I currently have a set of GP5000 28s fitted, just not sure if I would notice much difference going up to a 30 or 32 speed wise. At the moment I run 85/90psi i was thinking if I went to 30's maybe drop to 75/80 and 32s 70/75, I weigh about 90kg. The roads around me aren't the greatest hence thinking of going up in size I just don't want anything that feels sluggish, though my bike isn't aero and I'm hardly lightweight i average about 19mph on my solo rides

[ABogle]

85/90 sounds very very high for a 28 on a 24 int rim.

When I put your details and weight into the sram pressure calc (its usually quiet good) https://axs.sram.com/guides/tire/pressure I get just 66/70. Just try lowering the pressure for and see how it feels before you buy new tires, dropping 20 psi on your 28s will make more of a difference than moving to a 32 with the pressure still too high.

I would not bother going to widers tires unless your roads are quite bad (mine are), but if they are just go buy some 32s and see how they feel, it will help if you constantly have to deal with your bike vibrating on crap roads all the time.

[daninplymouth]

85/90 sounds very very high for a 28 on a 24 int rim.

When I put your details and weight into the sram pressure calc (its usually quiet good) https://axs.sram.com/guides/tire/pressure I get just 66/70. Just try lowering the pressure for and see how it feels before you buy new tires, dropping 20 psi on your 28s will make more of a difference than moving to a 32 with the pressure still too high.

I would not bother going to widers tires unless your roads are quite bad (mine are), but if they are just go buy some 32s and see how they feel, it will help if you constantly have to deal with your bike vibrating on crap roads all the time.

Thanks for your feedback, I did think they maybe a bit high, so I think your right I should try a bit lower first. I'm not uncomfortable but seeing as the roads seem pretty rough I was wondering if jumping up a couple of sizes might have a positive impact. Just weren't sure how the 32s feel and whether there is a noticeable difference in speed or if it's more in how they feel

[RNAV]

I run GP5000 TL 25s on one bike, and GP5000 TL 32s on a different bike and use both for A group rides. The 32s are more comfortable, and in my experience, just as fast. As previously mentioned, consider lowering pressure on your current setup. I checked the sram link provided and its suggested pressures are higher than my preferred Silca Pro Pressure Calculator. So according to Silca, you should likely be running even lower pressures than what Sram recommends.

That said, if you've got clearance for 32s, I'd say go for it. The 32 GP5000 TLs definitely do not feel sluggish.

[ABogle]

I run GP5000 TL 25s on one bike, and GP5000 TL 32s on a different bike and use both for A group rides. The 32s are more comfortable, and in my experience, just as fast. As previously mentioned, consider lowering pressure on your current setup. I checked the sram link provided and its suggested pressures are higher than my preferred Silca Pro Pressure Calculator. So according to Silca, you should likely be running even lower pressures than what Sram recommends.

That said, if you've got clearance for 32s, I'd say go for it. The 32 GP5000 TLs definitely do not feel sluggish.

The Silca calc seems to be heavily dependent on the 'surface condition'. If I select poor 'pavement/chipseal' (which is what i sadly have to select) only then does it give me a lower pressure than the sram calc. Tbh You can't go too wrong with either calc.

[C36]

The pressures you list appear high for the pavement you list. You will improve in comfort and performance by dropping 8-10 psi (around 80psi)
- you will have more confort cause the tire “spring rate” will be lower (more deflection) but not low enough to snake bite your tires
- you will be a bit faster cause the impedance losses (you bouncing around) will slightly drop.

Regarding the wider tires = more comfort, that’s not as automatic as marketing teams list it, if you drop the pressure accordingly to the width increase, then spring rate don’t change, neither the rolling… now if priority is comfort, wider tires will allow you to go quite lower without “snake biting”.

Regarding “sluggish” the wider and lower pressure you go, the more inert will the bike feel (never checked in detail but I would not be surprise you have quite more lateral deflection)

[daninplymouth]

I run GP5000 TL 25s on one bike, and GP5000 TL 32s on a different bike and use both for A group rides. The 32s are more comfortable, and in my experience, just as fast. As previously mentioned, consider lowering pressure on your current setup. I checked the sram link provided and its suggested pressures are higher than my preferred Silca Pro Pressure Calculator. So according to Silca, you should likely be running even lower pressures than what Sram recommends.

That said, if you've got clearance for 32s, I'd say go for it. The 32 GP5000 TLs definitely do not feel sluggish.

I'm running tubes at the moment and probably won't bother going tubeless for sometime.
My bike will fit the 32s fine, tempted to try them it's just their so bloody expensive these days I didn't want to order a set up then regret it

[daninplymouth]

This is typical of the roads I ride, not properly smooth with a few ruts to avoid

[Aesch]

I regularly ride 28mm tyres on my road bikes, my gravel bike however is 32mm gp5000 with latex tubes when setup for road (different wheelset). I'm always surprised how fast it feels.

[robeambro]

A lot of people get so obsessed with the 105% rule without giving half a thought about what tyre size and pressure is fastest for the surfaces they ride on.

I ride on nasty rough pavement and I've never ridden as fast as I am now on 30mm GP5000s - hardly aero on my 28mm wide rims.

[Mocs123]

I wonder if that's because the decrease in rolling resistance on poor pavement with wider tires is higher than the increase in aerodynamic drag by using wider tires than the wheel (ie. not complying with the 105 rule).

[ABogle]

I wonder if that's because the decrease in rolling resistance on poor pavement with wider tires is higher than the increase in aerodynamic drag by using wider tires than the wheel (ie. not complying with the 105 rule).

Possibly yeah. If you can feel your bike vibrating even with a sensible pressure, a wider tyre would be faster.

I guess it depends how much of your ride is on bad roads. I did a century this morning on a 28 at 69/66 and there were some awful bits of road but most them were not that bad. Some short bits would have been awful on anything but a gravel tyre but obviously it wouldn't be worth running that just for a few minutes out of a 5-6 hour ride. That said if my bike took a 30 then thats what I would be on.

[RNAV]

A lot of people get so obsessed with the 105% rule without giving half a thought about what tyre size and pressure is fastest for the surfaces they ride on.

I ride on nasty rough pavement and I've never ridden as fast as I am now on 30mm GP5000s - hardly aero on my 28mm wide rims.

Yeah, I've noticed that some of my highest solo average speeds for rides I regularly do are on my bike with 32s (Specialized Crux running cheap Superteam 40s). My "fast" bike weighs slightly less than the Crux, and has higher-end 60mm deep wheels running 25s . . . so theoretically, my fast bike should be faster. But it that doesn't seem to be the case. And yes, the roads around me are in pretty rough shape.

[DaveS]

Try the tire pressure calculator at zipp.com. Also be sure that your pressure gauge is accurate. My old silca was reading 8 psi higher than actual, before I replaced it with a much larger 0-100 psi model.

[neeb]

There are many, many factors to consider.

Another one is how fast you are actually riding generally, before you start considering tyre width. The faster you are going the more important the aerodynamic component will be in the trade-off equations, so the fastest tyre width on a given surface at 17mph may not be the fastest tyre width on the same surface at 21mph.