What size tires should i use before i lose low gearing

[nzdm1]

Hi,

I have a 85 safari swb sd33t. im wanting to get some good mud tyres as a second set for 4wd use only, but am unsure on the size i should go to.

What are your thoughts. 33" 34" 35" ?

im looking at some these: Simex Jungle Trekker 2 33/11.5-15 (Twin Block)
http://www.4wdbits.co.nz/ProductDetails ... oductID=23

but they are actualy 34.2" tall.
will this effect the power of the sd33t to turn these or will i be ok for 4wdriving im not sure what gearing i have but 5th gear driving hard is about 50km/h in low 4wd.

what are your thoughts please...

[wopass]

unless your going to do some hard core rock crawling the 33" trekers will be fine