As far as latex I've just used normal sized tubes in big tires without an issue. I've found the Grand Bois tires to be tough to get on, so if you find the Eroicas to be harder than those they must be tough.

Still Im not understanding how the tube is and issue. I put one bead on then bput the tube on and stuff it into the tire, rim channel, then put the other bead on. Not quite picturing your problem.

BTW, Have been using the same set of Challenge Paris-Roubaix 27mm tubie for 2 seasons on multiple Kermesse type races and no issues with punctures. I ride them at the minimum recommended psi. performed really well.

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Racing and Training Cycling Tires
www.tiremaniacs.com

Martin, which bike (and brakes)? Do they clear easily?

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Bikes: Raceur, Beateur

I couldn't get my 27mm PR to mount onto some DT 1.1 rims, stretching, and days of effort and still nothing. I swapped them onto a set of Roval wheels, and though they were hard, they went on decently well. I'm sure the actual rim size had something to do with it. Glad I didn't get them onto the 1.1s, I'd shudder to think what a roadside flat fix would be like!
My 27mm tires inflate to 30mm wide on the Roval wheels, which are 22mm wide external, 17mm wide internal...and plenty of clearance on my S-Works Roubaix.

2009 Jamis Xenith SL with Sram Red brakes and Reynolds MV32 tubies is my Kermesse bike. There was a micro touch of the tire against the front brake so I filed the caliper a bit.

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Racing and Training Cycling Tires
www.tiremaniacs.com

I have a set of paris roubaix lying in the cupboard they dont fit my colnago ep or my merckx mx !);

Challenge also has the new Strada tyres in 25mm width.

Finally some new info from the horse's mouth regarding puncture protection:

viewtopic.php?f=4&t=106642#p953039

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Bikes: Raceur, Beateur