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GP4000 did but they're not likely in stock any more.
GP Urban 35mm comes out more like 34mm but that's no use.
It really depends on your rims anyway. I never measured them but I wonder if GP4000 25 came up big like the 28s? You might find some of those kicking around. Or 4Seasons.Oh, Pro Optimum (Front) were 25 but came up 27 by design. Problem is I bought all of them for racing on about 10 years ago and they don't make them now. I think I have a new one still but it's a fair bit of hassle just to find out a tyre doesn't fit.
It's not looking super-likely though if you've got skinny rims, the 28s will tend to stay a bit skinnier, obvs so it might fit with enough room (especially if you're only on road where mud isn't much of an issue). But with older steel frames you'd tend to get a bit of flex so you might find if they're too close they'll rub but only occasionally. If you're near west london I have a fucked 28mm Pro4 Endurance (which are actually true to size unlike GP4000 which are more like 31-32mm) you can try for size.
Turbo Cotton come in 26 but I think the carcass is the same as the smaller size and just the tread rubber is wider. Also expensive and race tyres so not so durable.