I have 740 and original aluminum rims 14" with 185-70-14 tires. I have been thinking about improving ride and handling by changing the tire size but not wheels. OK guys what I can do and does it make sense at all !?
Thank you for your opinions.

Anthony

I know you said that you didn't want to change the wheels but The Turbo models usually came with 15 inch wheels while a base 740 just came with 14 inchers. The factory 14 inchers just looked (and felt) too small for my '86 740, so I grabbed some 15 inchers off of a junked '86 turbo. I think they had BFG 185 95 R15 touring tires. My 740 rides alot better and looks better too with the 15 inchers. I paid a about $20 apiece with plenty of tread to burn. A pretty cheap upgrade. (I love going to the junkyard!)

proboblt your best be is to switch to a sofer composite tire that is sligtle wider with a lower profile, this would noticibley improve your grip and inspire a little more confidance at high speed. if you want less grip that try a harder comp. tire, id personaly go with perelli's if you can aford them there about as nice and as soft as they come, and also yokohoma or bridgstone for a hard composite, thay'll last forever and drift quite evenly if pushed for grip.
it all depends on what youlike as far as handeling goes. and what ever anyone says never go with taller thinner tires for any kind of performance claim. hope that helped.

a 195/65-14 will give a slight advantage with little speedo error.

a 205/60-14 will give a little more, but your speedo will be high by 2%

The only way to ensure proper speedo calibration is to match the circumfrence of the new tire with that of the factory spec'ed tire. Tire sizes reflect a ratio comparing tread width with sidewall height. Not all 195-65 15 tires will measure the same in circumfrence and that is the measurement by which your speedometer is calibrated.
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There are no stupid questions only those that are not asked.

I don't know what tire you have on now but you might find better performance in a same size premium tire.

I've just found this on tirerack.com

http://tirerack.com/tires/tires.jsp?tireMake=Bridgestone&tireModel=Turanza+LS-T&vehicleSearch=true&partnum=87TR4TLS&fromCompare1=yes

The survey ratings look very good. BTW, just my opinion, I have Bridgestone RE730s on my 855t and while they're a fantastic tire, they're directional, meaning they must rotate in a specific direction when on the car. I won't buy directional tires again. I like to be able to put any tire on either side of the car in the event I need to.
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Erwin in Memphis, '88 745t 183,000 miles, '95 855t For Sale