Robert,in looking about I found a couple of things that may or may not be a help.On rootsireland.ie they have birth certs for both Winifred Dunn and Timothy Donovan for various years in county Tipperary.
Births: Timothy Donovan1833,1834,1837,1841
you would have to buy credits to look at the records.There is no record of a marriage between Timothy Donovan-Winifred Dunn on the site.There is a marriage for Winifred in 1857 county Tipperary which would be about right except the spouse isn't coming up as Timothy Donovan,unless he may have another forename or diff. spelling of his name. I then looked at immigration and found the following:
Winny Donovan born @ 1862imm 1882 Timothy Donovan born @ 1860imm 1883 Timothy Donovan born @1864imm 1882 Pat Donovan born @ 1862imm 1883 (came with Timothy) James Donovan born @ 1865imm 1883 Margaret Donovan born @ 1869imm 1885
I checked the civil registration lists and found births in county Tipperary for all of the above.You know about James and Maggie already but I'm thinking that Winny and Timothy may be brother and sister to James and Maggie as both forenames were very rarely used in Ireland at the time.
I found these and thought these may or may not be connected to your Timothy.
Prison Registers: for Timothy Donovan
born 1832imprisoned 1852 Clonmel,Tipperary no charge listed born 1846imprisoned 1863 Clonmel,Tipperary no charge listed born 1845imprisoned 1868 Clonmel,Tipperary no charge listed born 1847imprisoned 1870 Clonmel,Tipperary charge: assault
the last three may be the same man as birthdate is within year of each other.
Lastly,looking at Griffiths Valuation 1848-1864,no Timothy Donovan appears anywhere in co Tipperary.There is a Winifred Donovan listed at Shanavally,Cloghprior,Tipperary but no way to know if this is Tim's wife or another Donovan.Two Dunnes appear in Ballingarry,a Mary and a John.Going back a bit further to the Tithe Applotment books which generally cover 1814-1833 there are quite a few Donovans listed in Tipperary but none in Ballingarry,whereas the Dunnes are listed at least 15 times in Ballingarry so you can assume that Winifred's home village was Ballingarry.
What you could do is check the parish registers at the nearest LDS(Latter Day Saints) Library where they have them on microfilm. for Ballingarry: baptisms Feb 21,1842-Feb 7,1876 also Jan 4,1875-Dec 13,1880 marriages Apr 10,1842-Feb 22,1876 for all of Tipperary you need to check the dioceses of Waterford and Killaloe which both have various Tipperary parish registers. Hope this helps,Kim