I have a set of 15x6 rims wrapped in 195-50/15 tyres. But I'm soon gonna be purchasing a set of 15x6.5 rims. Would my current tyres easily swap over, or should I consider upgrading to 205's? That is, would the 205's be a better fit?

However, I think that my ride originally came in 195-55/15's (I could easily be wrong, though - maybe it was 185-55/15's?). So maybe it would be better for me to get the 205-50/15's anyway. What do you guys think?...

I have a 98 Civic SiR HB (Jap-spec). I'm guessing the rims & tyres would be the same as that of the USDM 99-00 Si (which you guys are more familiar with).

 

205s are better, but you have the 195s so just swap them over until they are worn out.

 

I wouldn't say that 205s are better. Not necessarily. It depends on what size tire your car originally came with. For example, on a car whose original tires were around the same outer diameter as 195/50-15 - which includes most older Civics that came with 175/70-13 or 185/60-14 - you're better off sticking with 195/50-15, for several reasons: (1) the speedometer and odometer accuracy will be maintained; (2) whatever you might gain in handling from 205 (and that's debatable), you will in turn lose from the slower acceleration from a tire that's larger than stock; (3) the 205 may rub; and (4) the 195 will be less expensive (sometimes substantially so).

The USM 2000 Civic Si came with 195/55-15 tires from the factory. If 195/55-15 is available in the tires you want, then go with that size. There are a lot of very good tires in that size, including budget performance tires like the Kumho Ecsta SPT and Yokohama ES100, or for a little more money, the excellent Toyo T1-R. The 205/50-15 is smaller in outer diameter (by 1.6 percent). 215/50-15 is actually a good match in diameter, but often results in rubbing on cars built for 195/55-15 (like most Integras).

Most 195/50-15, 195/55-15, and 205/50-15 tires are approved for use on rim widths of 5.5 to 7.0 inches, so you should be fine on 15x6.5 rims. You can double-check by going to the Tire Rack website or the tire manufacturer's website, and looking up the specs for the particular tire model and size you're considering.

All of which is a long way of saying that the answer to your question is "yes".

 

i prefer a wider contact patch over matching my speedo

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Mike C &raquo;</TD></TR><TR><TD CLASS="quote">i prefer a wider contact patch over matching my speedo </TD></TR></TABLE>

I prefer faster acceleration over slower acceleration.

 

faster acceleration is negated when you're leaving the corner 2mph slower

 

Faster acceleration is better when there's no way in hell 10 mm of treadwidth is going to give you an extra 2 mph in the corner.

 

you have any data to back that up?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Mike C &raquo;</TD></TR><TR><TD CLASS="quote">you have any data to back that up? </TD></TR></TABLE>

Yup - all the people with wider tires whose asses I whup at the track.

 

Thanks for the input, guys.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by nsxtasy &raquo;</TD></TR><TR><TD CLASS="quote">Faster acceleration is better when there's no way in hell 10 mm of treadwidth is going to give you an extra 2 mph in the corner.
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<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Mike C &raquo;</TD></TR><TR><TD CLASS="quote">you have any data to back that up? </TD></TR></TABLE>

I've seen two different articles in which different size tires were tested against each other. (One was in BMW CCA's Roundel magazine, the other in Grassroots Motorsports.) Unfortunately for our purposes, both consisted of different size wheels as well, where the wider tires were placed on larger wheels, and the outer diameter of the wheels was kept constant - more on these conditions in a moment. In both cases, average lap times improved slightly (by about a tenth of a second in a one-minute lap) as the wheel size was increased from 15" to 16" and to 17" (and tread width increased); in one case, lap times worsened when going to 18", in the other they stayed about the same. That average improvement was less than the lap-to-lap differences in times, so it's not clear whether that was just "noise" or actual improvement. In any case, the differences were nowhere near the two seconds you would get if you improved your speed through the turns by 2 mph.

Furthermore, a good part of whatever improvement there was in these questionable test results, may be due to the use of larger wheels and shorter sidewalls, with quicker handling response, rather than the wider tread width. Also, the tire sizes selected had the same outer diameter, so there was no degradation of acceleration the way there would be when your wider treadwidth is accompanied by a larger outer diameter.

 

oh stoppp, the 2mph was an exaggeration, but you get the idea.