Even if its just a rubber, by putting on the 50mm tire wall on the same rim, you will reduce the rotating mass of the overall wheel so you have improved performance and a rim that looks bigger........ I remember I felt a slight improvement in acceleration and deceleration when I did that.lol spot on Manos, your right. So you reccon its best of sticking with 195/55 15's?
Thing is, I'm used to using GoodYear Eagle F1's, and can only find them in 195/50 15's, not 55's
You will gain a little bit if you drop something like 30mm because the weight goes with it, but you can't seriously feel 5mm. Thats just exagerating... It's like saying taking off my floor mats will give me better acelleration...
vtecroadhog: If I can remember, the ctr offsets are 195/55 +50 or 55. I'm pretty sure it was +50 as I was lowering my car last month. 205 just looked fat and funny. It did rub with 205 but not now with 195.
The overall diameter of the 195/50 is 19.5mm less than the 195/55, the 205/50 is 9.5mm smaller than the 195/50. This raises the final drive ratio, which lowers top speed but does make the car accellerate faster. The farther the tire size is from stock (overall diameter) the bigger the change in the FD ratio.
To give a rough idea, a 195/50 will spin 29 more times than a 195/55 over the course of a mile.
A 195/50 is about 1 pound lighter than a 195/55, and that is 1 pound lighter than a 205/50, on average. I feel the extra grip of a 205/50 gains more than the 1 less pound of unsprung weight of the 195/55, in both accelleration and cornering.
I wouldn't put a 205/50 on a stock ek9 wheel, because its only 6" wide and with some tires there will be rubbing at full lock. However, I had a 15x7 +41 enkei RP-F1 with a 205/50-15 tire, and there was no rubbing.
Jugbugz- Removing floor mats does make way for better accelleration, why so suprised? You said that the 205/50-15 looked fat and funny, don't you realize there is a performance gain with a wider tire? (fitment issues nonwithstanding) IMO a 205/50 looks fat and awsome.
And when you mention the 5mm difference in circumference, I think your way off, the difference in circumference between the 195/55 and the 195/50 is 61.2mm, and 29.8mm smaller for the 205/50.
Djaniero- The eagle f1 gs-d3 is a good street tire, but they don't make it in a suitable 15" size for the EK. Look for a 195/55, and if your wheel size and offset permits, go for a 205/50.
While I have not taken the liberty to calculate the factual differences in figures, Dino stated that the 60mm difference is on the circumference, not the diameter.
Also 195/55/15 and 205/50/15 does have a rough 5mm difference in the height of each of the side walls, indeed making the total tyre diameter of the 195 larger by roughly 10mm. The idea is that the two tire sizes are the closest for that specification hence everyone saying that they are the same, but fact is there are always slight differences between tyre sizes, as well as in 195/55/15 to 205/45/16 conversions. The 205/45/16 is actually smaller in diameter. Strictly speaking they are definately not of the same size.
Jugbugz, your idea of " Spinning 29 times more over a mile doesn't mean it's accelerating faster " is like saying having the 4.7 or 4.9 FD doesnt mean the car is accelerating faster.
Both a smaller wheel and a shorter final drive work on the principle that the same amount of energy produced by the engine is converted into less distance covered, hence the energy is per work involved is higher, i.e. faster acceleration. And you have to understand that the small difference in circumference becomes very large in effect when you are spinning the wheels as fast as cars are.
If you are skeptical you can do a comparison by swapping a big wheel from another car unto yours and do a time comparison with a smaller wheel over a same distance.
Personally I am able to tell small differences well enough to notice the gains. Im not kidding when I say I can feel a 3hp difference when I pay attention. And the improvements from having a 195/50/15 wheel as compared to 195/55/15 across the whole rev range and stretch of road turns out to be very significant by the end of the session.