You will find that the Trojan Magnum XL is a bit wider than the regular Magnum. I got by with the Magnum XL until They Fit became available.
As far as I know, there are no over the counter condoms wider than the Magnum XL available in the USA. The main reason for this is that FDA makes it difficult to sell condoms which are wider than 54 mm along at least some portion of the shaft when flattened. This is discussed in the FDA guidance document:
Latex Condoms for Men
Information for 510(k) Premarket Notifications: Use of Consensus Standards for Abbreviated Submissions
which you can read online on the FDA website:
http://www.fda.gov/cdrh/ode/ltxcondm.pdf
In order to sell wider condoms, a more complex approval FDA process is necessary, with which most manufacturers can't be bothered. The They Fit condoms got around the FDA rules by having you measure your penis in order to select the correct size. This mitigates concerns of someone inadvertently buying too wide a condom and having it slip off, which is the reason for the FDA rule regarding maximum width.
I strongly recommend the They Fit condoms. I use size U22, and have found they make a world of difference over the Magnum XL. While I used to fumble awkwardly to get into the Magnum XL, the U22 goes on fairly easily, and is much more comfortable. In addition, the proper fitting condom gives much better sensation. It's well worth the effort of ordering online. I usually buy 12 dozen or so at a time to make the ordering less of a frequent hassle. Condomainia gives a discount on larger orders, and frequently emails discount codes for even more money off. As I result, I actually pay less than I did for Magnum XL's over the counter at my local pharmacy.