Tyre intended to equip a vehicle bearing heavy loads, this tyre comprising a tread including at least one rubber composition based on at least: - an elastomer matrix predominantly comprising a copolymer based on styrene and butadiene having a glass transition temperature Tg strictly above -65°C and below or equal to -30°C, - a reinforcing filler predominantly comprising silica, - a chemical crosslinking system, - an agent for coupling between the elastomer matrix and the reinforcing filler, - a plasticizing system comprising from 2 to 15 phr, preferably from 2 to 10 phr, of at least one plasticizing resin having a glass transition temperature Tg of greater than or equal to 20°C, and of which the total content of the plasticizing system in the composition ranges from 2 to 17 phr, preferably from 2 to 12 phr, and - an agent for modifying said copolymer based on styrene and butadiene, optionally already grafted onto said copolymer, said modifying agent being a 1,3-dipolar compound of general formula: A-E-D o the symbol D represents a functional group comprising at least one nitrogen atom and being capable of bonding to said copolymer via a cycloaddition of [3+2] type on a carbon-carbon double bond of the chain of said copolymer, o the symbol E represents a divalent spacer group connecting group D to group A, o A represents a functional group chosen from C 1 -C 20 alkyls, C 7 -C 18 alkylaryls, C 7 -C 18 arylalkyls, optionally substituted nitrogen-based heterocycles of 5 to 6 atoms, optionally substituted sulfur-based heterocycles of 5 to 6 atoms, ester groups, phosphate groups, dialkylamino groups and associative groups comprising at least one nitrogen atom. - an elastomer matrix predominantly comprising a copolymer based on styrene and butadiene having a glass transition temperature Tg strictly above -65°C and below or equal to -30°C, - a reinforcing filler predominantly comprising silica, - a chemical crosslinking system, - an agent for coupling between the elastomer matrix and the reinforcing filler, - a plasticizing system comprising from 2 to 15 phr, preferably from 2 to 10 phr, of at least one plasticizing resin having a glass transition temperature Tg of greater than or equal to 20°C, and of which the total content of the plasticizing system in the composition ranges from 2 to 17 phr, preferably from 2 to 12 phr, and - an agent for modifying said copolymer based on styrene and butadiene, optionally already grafted onto said copolymer, said modifying agent being a 1,3-dipolar compound of general formula: A-E-D o the symbol D represents a functional group comprising at least one nitrogen atom and being capable of bonding to said copolymer via a cycloaddition of [3+2] type on a carbon-carbon double bond of the chain of said copolymer, o the symbol E represents a divalent spacer group connecting group D to group A, o A represents a functional group chosen from C 1 -C 20 alkyls, C 7 -C 18 alkylaryls, C 7 -C 18 arylalkyls, optionally substituted nitrogen-based heterocycles of 5 to 6 atoms, optionally substituted sulfur-based heterocycles of 5 to 6 atoms, ester groups, phosphate groups, dialkylamino groups and associative groups comprising at least one nitrogen atom. o the symbol D represents a functional group comprising at least one nitrogen atom and being capable of bonding to said copolymer via a cycloaddition of [3+2] type on a carbon-carbon double bond of the chain of said copolymer, o the symbol E represents a divalent spacer group connecting group D to group A, o A represents a functional group chosen from C 1 -C 20 alkyls, C 7 -C 18 alkylaryls, C 7 -C 18 arylalkyls, optionally substituted nitrogen-based heterocycles of 5 to 6 atoms, optionally substituted sulfur-based heterocycles of 5 to 6 atoms, ester groups, phosphate groups, dialkylamino groups and associative groups comprising at least one nitrogen atom.