Section 1, Coverage C, personal property: We insure for direct physical loss to the property described caused by a peril listed below, unless the loss is excluded in Section 1 exclusions. Paragraph 9, Theft (so theft is covered). C. From that part of a ‘residence premises’ rented by an insured (doesn’t apply here). This peril does NOT include loss caused by theft, that occurs off the ‘residence premises’, of (sub paragraph A) property while at any othe rresidence owned by . . .an insured.

So. The reason why stuff stolen from your car is covered, off premises, is because the property coverage applies worldwide on the standard policy. And the reason the lawnmower wasn’t covered, is because it was at another residence owned by you. Presumably, you should have some contents coverage for that residence.

BUT, big hint here . . .that lawnmower is a MAINTENANCE item. Presumably, it’s there to mow the lawn of your rental property. If that’s the case, on a standard homeowners/dwelling policy, it’s actually covered, FOR THEFT, under the BUILDING section, subject to the policy deductible.

So, I think you can find coverage for it under THAT policy, even if you don’t have any contents coverage.