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GP4000 SII Experience?

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GP4000 SII Experience?

Old 12-17-16, 09:02 PM
  #26  
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Originally Posted by twocicle View Post
I haven't used Vittoria Rubinos since circa 2005 on my single. The tires I rode (don't know if there was a further model delineation other than just "Rubino") punctured easily and the tread rubber had poor cornering grip which almost failed me many times and finally did result in a crash on a wet March road. Maybe the Pro Tech III are better than whatever I used back then. Might be worth a look.
The Rubino series has undergone a series of iterations since you've used them. The Pro Tech III was built during one of those iterations and is not made any more though it is still available. The latest is the Rubino Pro G+, which doesn't have the lowest RR as a light training tire though it may have other good qualities. There's also a Rubino Pro Control G+ which is marketed as more of a winter tire with good sidewall protection and is available in 28 mm. Might be nicer than the 4-Seasons.
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Old 12-18-16, 10:26 AM
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Sort of depends on what you are shooting for... a high puncture resistant tire with ok ride feel and rolling, or a slightly faster tire with a little less rolling. Maybe factor in cost too.

FWIW, here is a good source for tire tests, that for all intents and purposes offers an apples-to-apples comparison. Unfortunately there is no "ride quality" test data...

Vittoria: Road Bike Tires Rolling Resistance Reviews
Continental: Road Bike Tires Rolling Resistance Reviews

The GP4Season tests show a lighter weight and much higher puncture resistance (17/7) than the Rubino Pro G+ (12/5), but the latter has a slightly better rolling resistance and lower price.

This of course is only comparing 2 mfr. Others like Specialized Armadillo would be nice to see the data, but no tests on this site for those tires.

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Old 12-18-16, 03:24 PM
  #28  
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Originally Posted by twocicle View Post
Sort of depends on what you are shooting for... a high puncture resistant tire with ok ride feel and rolling, or a slightly faster tire with a little less rolling. Maybe factor in cost too.
We've been riding on Continental Gatorskins 700x32 (wirebead) for the last several years so I have a good baseline with them. This was on a Santana Arriva and now we have a Santana Beyond and went with Continent GP 4 Seasons in 700x28mm (folding) for this was one of the (no cost) options the dealer gave us when we ordered the bike. We have about 1,800 miles on the bike and the Continent GP 4 Seasons and I'd say they are a hair more supple than the Gatorskins. We've not had a flat/puncture yet with the GP 4 Seasons and with only 1,800 miles on them I can't discern a difference in puncture resistance. Yet I was thinking of changing to something more supple/comfortable and am willing to give up a little puncture resistance. I assume the Continent GP 4000 IIS with their lower rolling resistance would provide a smoother ride. Do any of you have a idea of the difference in ride feel between Continent GP 4 Seasons & Continent GP 4000 IIS? Do you think we'd notice if we switched to the GP 4000IIS over the GP 4 Seasons?
We are a 350 lb team and most of our rides are flat, we live in South Louisiana .

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Old 12-18-16, 08:10 PM
  #29  
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We have experience with 28mm Gatorskins, 4 seasons and 4KS2 on our T2000. I notice the smoother ride with the 4KS2 compared with the other tires. The Beyond frame also provides a smooth ride, so it's possible that you might not notice as much of a difference as we did in our stiff Al frame.

The 4KS2 seem to wear well. We are a 320 lb team and even ride them occasionally on dirt/gravel briefly. No problems except the time I rode over a box of razor blades.
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Old 12-18-16, 11:11 PM
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Originally Posted by Chancy View Post
We've been riding on Continental Gatorskins 700x32 (wirebead) for the last several years so I have a good baseline with them. This was on a Santana Arriva and now we have a Santana Beyond and went with Continent GP 4 Seasons in 700x28mm (folding) for this was one of the (no cost) options the dealer gave us when we ordered the bike. We have about 1,800 miles on the bike and the Continent GP 4 Seasons and I'd say they are a hair more supple than the Gatorskins. We've not had a flat/puncture yet with the GP 4 Seasons and with only 1,800 miles on them I can't discern a difference in puncture resistance. Yet I was thinking of changing to something more supple/comfortable and am willing to give up a little puncture resistance. I assume the Continent GP 4000 IIS with their lower rolling resistance would provide a smoother ride. Do any of you have a idea of the difference in ride feel between Continent GP 4 Seasons & Continent GP 4000 IIS? Do you think we'd notice if we switched to the GP 4000IIS over the GP 4 Seasons?
We are a 350 lb team and most of our rides are flat, we live in South Louisiana .

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Yes, I think you'd notice right off. Those 28mm 4KIIs are really big so run them a little softer. If you get flats off the anti-flat strip, run them a little harder.
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Old 12-19-16, 09:41 AM
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Charlie,

Tire width and psi used makes a big difference regardless of which tire you use. Yes the 4K is a lighter more supple tire than the 4Season and the 4K measures a good tire size more than the indicated size.

With the 4Seasons, I'd say teams < 300lbs would use the 28mm, and teams over 300lbs would like the 32mm better. Do note that each tire size would have a ~10psi difference (bigger tire = less psi as it has more air volume).

For the 4k tire, the 28mm bloats out to at least 31mm on most rims.

If you ride through a lot of road debris or rough roads, I would suggest the 4Season, otherwise the 4K. For teams over 400lbs, probably a different type of tire than either of these.
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Old 12-19-16, 10:39 PM
  #32  
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Thanks for all the comments. When I wear out our current GP 4 Seasons (700x28mm) I thiink we'll give the GP 4000 SII a try (in 28mm).

Tailwinds,
Charlie
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Old 12-22-16, 03:43 PM
  #33  
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Matching up tire size with your rim width and optimal aero shape does affect both ride quality and performance.

I just did a +1 on my S-Works Tarmac single to test the 4ksII 25mm on a set of Rolf Prima Alpha wheels. I've run the 4ksii 23mm @ 106psi on these wheels for a few years now, and so very well attuned to those. After a couple rides on the 25mm (at 100psi, then 95psi) they definitely reduce some of the minor vibration but have little benefit on the bigger frost heave hits or rough chippy type road surface, plus a number of times it felt like my brakes were dragging - mostly in crosswind situations. The Rolf rims are not super wide - only 22mm outside, I think, and so the 25mm tires seem to be a bit too wide to work well aerodynamically. Definitely results a more bulbous shape than on our tandem carbon wheels that have much wider rims. IMO, the 23mm work much better on these particular wheels.

We just received a couple 28mm 4ksii tires to put on the tandem (upping from 25mm) and test over the next few weeks (we're hanging out in Tucson for some sun). The 28mm might be too big for good clearance with our Whisky #9 road fork, but the bigger tire should work fine if only on the rear wheel. TBD.

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Old 12-23-16, 02:59 PM
  #34  
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Originally Posted by joe@vwvortex View Post
We've had the opposite experience. Two Schwalbes blew the casing for no reason after 2 rides. Our Conti 4000 II's on the other hand have been flawless over the past year.
Have been using Conti GP4000S for a long time and really like them.
I have always been skeptical about Schwalbe and there seems to be a lot of complaints about quality and premature failure.
But recently I decided to try Schwalbe One (not tubeless) on my single bike and I have to say I really like the ride and they are holding up really well. So I am now considering trying them on the tandem, at least on the front.
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Old 12-24-16, 12:28 PM
  #35  
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Originally Posted by jnbrown View Post
Have been using Conti GP4000S for a long time and really like them.
I have always been skeptical about Schwalbe and there seems to be a lot of complaints about quality and premature failure.
But recently I decided to try Schwalbe One (not tubeless) on my single bike and I have to say I really like the ride and they are holding up really well. So I am now considering trying them on the tandem, at least on the front.
They did have a nice feel to them for the first couple rides but then....

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Old 12-24-16, 02:22 PM
  #36  
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Originally Posted by joe@vwvortex View Post
They did have a nice feel to them for the first couple rides but then....

Had exactly the same thing happen to two different Schwalbe One tires. Since they were my special event tires, really ruined things twice. They were a couple of years old, but never used. Hopefully they have gotten better?
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Old 12-26-16, 10:35 AM
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Originally Posted by bwebel View Post
Had exactly the same thing happen to two different Schwalbe One tires. Since they were my special event tires, really ruined things twice. They were a couple of years old, but never used. Hopefully they have gotten better?
Me too. One bought online - and one bought at a local shop to replace the first one that went bad. Thought it might have been a run a of bad ones at first but ..........

ON the other hand a friend has ridden them on his tandem for years without a problem.
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Old 12-28-16, 08:00 PM
  #38  
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Initial 50 mile ride done on the 28mm 4ksII (rear only). Mounted on the wide LB carbon rims, the 28mm looks HUGE. If you relate a 23mm 4ksii to your pinky finger, a 25mm to your index, the 28mm is akin to a fat thumb.


I left the tire mounted and pumped to 110psi for a couple days to stretch out, then set to 95psi at the start of our ride. Linda's feedback was for a slight improvement over the 25mm. Then mid-ride I let a little air out to see how that felt. Along with a temperature drop of some 14F, the final psi measured back at home (RV) was only 88psi. Linda had commented the ride was very nice but she thought the tire may be a little too soft and slightly bouncy. She was probably correct since I was shooting for not less than 90psi for the 28mm rear, and 104psi for the 25mm front. 92psi is probably going to be our target for the rear (a far cry from the 25mm 4-Seasons pumped to 118psi that we used a few years ago on skinny Spinergy rims).

A bit more perspective we are acquiring this winter: I had to give Linda her very own pecan pie for Christmas cause her weight was slipping under 93lbs. Our combined team body weights currently come to 253lbs. We usually ride fairly smooth roads, and so haven't had the need for squishy tires or cushy seatpost dampers. However, spending a bit more time on less than ideal roads here and there in CA and AZ had us looking for more comfort. At this point, I think these 28mm tires on the rear will be all we need for paved road riding.

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Old 12-30-16, 02:32 PM
  #39  
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I just mounted two 28 mm 4KS2s on Dyad rims. Left overnight at 100psi, they measure 32 mm wide.
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Old 01-01-17, 02:01 PM
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Yep, the Dyad is sufficiently wide enough with 18.5mm internal (by comparison, the Spinergy TX2 we had was 18.5mm external :/) to achieve a nice fat tire profile without incurring a bad "lightbulb" shape.

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Old 01-06-17, 10:21 AM
  #41  
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New to cycling and tandems as of last summer. After about a year of research and looking we purchased a used Co-Motion Supremo which came with 25mm GP4000-S tires. I had spent a lot of time researching stoker suspension posts and worrying about the comfort of my stoker and her willingness to ride the tandem. She loved the bike on the test ride and since then has never mentioned needing a suspension post. Our team weight is 225/145 so I run the tires at 125psi. We do not ride very hard and I expect our team weight will go down before we begin to ride more aggressively so I have pretty much quit worrying about the tires although I am cautious and don't corner at speed.

I initially thought we would not ride on anything smaller than 28mm but this is the largest tire that will work well with the compact brakes on the bike. We joined MyFitnessPal at the new year and our team weight has already dropped 3 pounds so hopefully, fingers crossed, we can get closer to 300 lbs. combined and then the tires will be more appropriate for our team.

The bottom line is the stoker is happy and she asks to go for rides. If the tradeoff is I change a few tires then so be it.

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Old 01-06-17, 02:34 PM
  #42  
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Originally Posted by twocicle View Post
Yep, the Dyad is sufficiently wide enough with 18.5mm internal (by comparison, the Spinergy TX2 we had was 18.5mm external :/) to achieve a nice fat tire profile without incurring a bad "lightbulb" shape.
I am not convinced that using wider rims leads to a less harsh ride.
In fact IME the same tires on wider rims at the same pressure ride harsher.
This leads to what most people do is to ride wide rims at a lower PSI.
I think the lightbulb shape tire actually rides smoother because there is more vertical distance that the tire can deflect. The advantages of wider rims as I understand it are improved cornering and tires can be run at a lower pressure.
I think these things are very subtle and subjective. I think wide rims are mostly a trend and most higher end rims are going that way. I did switch to wider rims mostly out of curiosity and while I am not convinced they are better there is no reason not to use them.
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Old 01-08-17, 11:46 AM
  #43  
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Originally Posted by jnbrown View Post
I am not convinced that using wider rims leads to a less harsh ride.
In fact IME the same tires on wider rims at the same pressure ride harsher.
This leads to what most people do is to ride wide rims at a lower PSI.
I think the lightbulb shape tire actually rides smoother because there is more vertical distance that the tire can deflect. The advantages of wider rims as I understand it are improved cornering and tires can be run at a lower pressure.
I think these things are very subtle and subjective. I think wide rims are mostly a trend and most higher end rims are going that way. I did switch to wider rims mostly out of curiosity and while I am not convinced they are better there is no reason not to use them.
Dead wrong and there is plenty of articles available to support that. Conversely you will not find any legit info portraying skinny rims and lightbulb shaped tires pumped to higher psi as providing a better ride.

Wider rims not only fatten the tire and improve the tire shape, but also allow for more air volume. This is why they are able to use less psi... the increased air volume compensates for that. The tire shape is an improvement because the sideways are not slopped excessively over the side of the rim. Many articles will show you why the lightbulb shape yields poor handling.

Of course, it is impossible to have everyone on the same page. Opinions are just that.
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Old 01-08-17, 06:15 PM
  #44  
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Originally Posted by twocicle View Post
Dead wrong and there is plenty of articles available to support that. Conversely you will not find any legit info portraying skinny rims and lightbulb shaped tires pumped to higher psi as providing a better ride.

Wider rims not only fatten the tire and improve the tire shape, but also allow for more air volume. This is why they are able to use less psi... the increased air volume compensates for that. The tire shape is an improvement because the sideways are not slopped excessively over the side of the rim. Many articles will show you why the lightbulb shape yields poor handling.

Of course, it is impossible to have everyone on the same page. Opinions are just that.
IIRC this light-bulb business is covered on Sheldon Brown. There's a table there giving acceptable rim width vs. tire size. I understand that many people scoff at this table and violate it all the time. I am also a violator and having violated, have an opinion.

Tires are still designed assuming the light bulb inflated shape because the vast majority of tire/rim combinations in use world-wide go by the Sheldon Brown table on this page: Tire Sizing Systems

Running tires much wider than the range shown in this table puts more sidewall on the road. Running lower pressures than normal puts even more sidewall on the road. This is a bigger deal with high performance tires with narrow anti-flat belts and thin, unreinforced sidewalls.

When I went with wider rims, I also reduced pressure as is usually advised. I started to get more sidewall cuts near the outside of the usual running surface and more flats. I went back to the old narrow rim pressures and got better results w/r to flats and cuts, but of course no smoother ride.

I also went way outside the table on my single, running tires of the same nominal width as the outside rim measurement. They did ride harder at the same pressure compared with running them on narrow rims because the vertical sidewalls are in compression rather than flexion. I reduced pressure from what I would use on a narrower rim and I think they still ride harder. But fine, I'll live with it because of the more aero tire/rim combo and because I think they do handle a little better. I find the ride quality acceptable, but not an improvement.

Note that 28mm 4KIIs tires are well within the table limits of our 23mm (outside) rims and work fine with them. Even so, I get best results at 105 lbs. for our (where are we today?) 285 lb. team. I tried it at lower pressure, 90 lbs., and got more cuts and flats, though still no pinch flats.
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Old 01-08-17, 09:28 PM
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^^^ This is sort of the point raised above... properly matching rim width to tire size to achieve the optimal tire shape, air volume and ride quality.

The Kinlin/BHS rim you are using is similar to the Dyad dimensions and close to the LB carbons we have. These rims all match well with the wide Conti 4kiis 28mm tire (31mm+).

Running tires much wider than the range shown in this table puts more sidewall on the road.
No, actually the reverse is true. In this case, much of the sidewall will be wrapping around and pinched in at the rim. The "Sheldon' page (written when and how long has he been dead?) simply says this "If you use a very wide tire on a narrow rim, you risk sidewall or rim failure. This combination causes very sloppy handling at low speeds.".

FWIW so far after a couple weeks of riding in Tucson, the 4kiis 28mm on on our rear wheel at ~95psi is working great, no cuts or flat issues whatsoever, which is saying a lot considering the miles of debris we rode through today on a couple of ill-selected remote sections. On the same rims, the 25mm 4ksII must be set to ~107psi to achieve similar handling and prevent excessive sidewall sag (ie: leading to pinches or rim damage). After pumping up the front (25mm) and rear (28mm) to those settings and doing a pinch test with fingers, both tires actually feel about the same firmness.

The 28mm has really won the test for when the road gets rough, where Linda was getting beatup on the 25mm. She is now 100% - No shock or suspension post req'd for the entire mix of roads we are riding here.

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Old 01-09-17, 01:15 PM
  #46  
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Originally Posted by twocicle View Post
^^^ This is sort of the point raised above... properly matching rim width to tire size to achieve the optimal tire shape, air volume and ride quality.

The Kinlin/BHS rim you are using is similar to the Dyad dimensions and close to the LB carbons we have. These rims all match well with the wide Conti 4kiis 28mm tire (31mm+).

No, actually the reverse is true. In this case, much of the sidewall will be wrapping around and pinched in at the rim. The "Sheldon' page (written when and how long has he been dead?) simply says this "If you use a very wide tire on a narrow rim, you risk sidewall or rim failure. This combination causes very sloppy handling at low speeds.".

FWIW so far after a couple weeks of riding in Tucson, the 4kiis 28mm on on our rear wheel at ~95psi is working great, no cuts or flat issues whatsoever, which is saying a lot considering the miles of debris we rode through today on a couple of ill-selected remote sections. On the same rims, the 25mm 4kiis must be set to ~107psi to achieve similar handling and prevent excessive sidewall sag (ie: leading to pinches or rim damage). After pumping up the front (25mm) and rear (28mm) to those settings and doing a pinch test with fingers, both tires actually feel about the same firmness.

The 28mm has really won the test for when the road gets rough, where Linda was getting beatup on the 25mm. She is now 100% - No shock or suspension post req'd for the entire mix of roads we are riding here.
Yeah, the 28/Kinlin combo is just killer for speed and smoothness. Magic carpet even on our old Speedster.

But take a loose tire, hold it up in front of you and bend it through the two sections, U-shaped and lightbulb, while holding the bead section vertical. It looks to me like the lightbulb does pull more sidewall up off the road.

Stoker, bike, and bag weight has a lot to do with rear tire pressure.
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Old 01-09-17, 07:24 PM
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Originally Posted by Carbonfiberboy View Post
It looks to me like the lightbulb does pull more sidewall up off the road.
I think we are now saying the same thing as far as sidewall goes. But a downside of that shape is that as the sides are pinched upward away from the road, so are the edges of the contact patch - reducing the amount of grip available. Plus with the necessary compensation increase in psi to stabilize that shape comes poorer rolling resistance values.

The 4ksII is definitely not bullet proof no matter what part of the tread or sidewall you want to look at. I've had a couple run-ins in Tucson with "thorn balls" (chunks of catcus spike balls laying on the road) which have yielded some slow tube leaks on my single (no flat on the tandem so far). No major cuts, just miro-hair prickles that will go through just about anything including sneaker soles as we discovered. All my liquid sealer and removable core tubes are back home, so ignoring this for now and just staying alert.

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Old 01-16-17, 10:23 PM
  #48  
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So I replaced the almost worn out GP4000S on the rear with the Schwalbe One 25c.
Part way through the first ride I asked my wife if she noticed a difference.
She said yes, less bumpy and more stable. We did our second ride on it today and no problems so far.
So I ordered one to put on the front. Hopefully they will be as trouble free as the ones I have had on my single for a few months, that bike gets less mileage than our tandem since most of my rides are on the tandem.
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Old 01-20-17, 12:33 PM
  #49  
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Hot Deal on GP4000

FYI - Good deal on GP4000S:

Continental Grand Prix 4000 S II Tire - Tires - Clincher - Excel Sports
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Old 01-20-17, 06:38 PM
  #50  
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We are currently on Dyad rims and are thinking about the 4000's as event tires. Would you recommend the 25's (since they evidently end up being 28's) or the 28's? we are currently running 28mm GP 4 Seasons, team weight is 305lbs, plus a 40lb bike. We use inner tubes marked as 19-26mm, if we get the 28mm 4000's, do we need to run bigger inner tubes?

Thanks for your help
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