Rep Power: 293

I just had new Falkens ZE 512 size: 205/55/16 installed yesterday and my car is lowered with Sportlines. I had chosen such a big middle number to fill in the huge gap that I had before with my 215/40/16.
The new tires filled up the gap that I had; but as a consecuence, now my tires are slightly rubbing and my car only when taking a sharp turn and it has a hard time reaching its top end speed, something that never happened before even on stock tires.
Is there anything I can do to prevent the tire from rubbing and the problem with the speed?
Opinnions are welcomed...

 
Rep Power: 0

the problem with speed doesnt make sense, ur new tires are just probably alot heavier than ur old ones. only way to get that back is boltons. about the rubbing u might want to roll ur fender, u can get up to an extra inch, might mean the world, also find out where its rubbing, becuase it might be the inside fender, in the middle of the car,in which case u are ****ed.

 
Rep Power: 379

Both the Rubbing and the Slower acceleration are Due to the tires sidewall height....


Put it this way, the 205/55-16 is a good 2" taller then the 215/40-16 (which would account for the rubbing.

for acceleration.... THe 205/55-16 is a good 8.54% "Taller" then the 215/40-16... which means that you've effectivly altered the final Drive ratio by 8.54% making the gears "Taller" = Slower acceleration.

 
Rep Power: 293

Thanks guys, that's exactly what's happening Zzyzx...on 5th gear the car takes a loooong time to get to 110mph. With the previous tires, I had no problem taking it over 115mph. I thought since these new tires are bigger it would take less rotation from point A to B, and therefore would be faster, but obviosly it doesn't work that way...
Crap...so I guess I'm stuck with these tires for at least 2 years cause I doubt that they'd trade them for some smaller ones...
I have so much to learn...

 
Rep Power: 379

Look at the bright side... with taller tires, you'll get better gas milage and Have a Higher Top speed..


BTW, what were the stock sized tires on your car... (I ask because you may have alleready altered the gearing on the car making your speedometer Read fast/slow.)

 
Rep Power: 293

^^^Oh oh, are you serious?
...so I may be driving faster than the actual speed shown on the gauges?
I don't like the sound of that, I might get pulled over for going 70mph when I'm actually doing 65mph. Is that what you meant? How much of a diference would it be?

 
Rep Power: 0

our precious tire calculator will show how far your speedometer gets off.

 
Rep Power: 379

Well, your profile says you have an LX...

the stock sized tire on the LX is a 185/70-14 which has an overall diamiter of about 24.25"

a 205/55-16 has an aproximat diamiter of 24.88" Making it 2.6% Taller then the stock sized tires... making your Speedomiter Read 2.6% Higher then you'r actual speed. (Meaning if your speedo Reads 70MPH, your actually going about 72MPH..) When you had your 215/40-16s with an overall diamiter of about 22.76", making it 6.17% shorter then stock.... making the Speedo read Faster then what you were actually going. (At 70MPH, you would actually be going only 65 MPH.... and at 100 MPH you were actually only going about 93.... and when your speedo Read 115 (as you stated earlier) you were actually only going about 108. (Gearing is fun)

So, if you want to tweak your acceleration... Taller tires then stock = Slower acceleration, Higher top speed. Shorter tires = Faster acceleration, Lower top speed.

 
Rep Power: 0

noob alert noob alert!!!!!

so how exactly do you go about making the speedometer correct using a different size tire?

let the flaming begin

 
Rep Power: 293

^^Might be a noob question, but I was wondering the same thing...

Zzyzx, I just looked at my stock tires and they are actually 195/60-15...appearently the numbers haven't been updated for 04-05 vics on this site...maybe 185/70-14 were for 01-03 models, I don't know cause I don't own one, but I think I might have to bend my fenders in the back as Vantage suggested giving me even more clearance.
These new tires I bought definately serve as a good lesson. Next time, I'm taking under consideration all these stuff...crap, I never imagined so much on the car can be affected by increasing/decreasing the tire sizes...(handling, rubbing, center of gravity height and even the acceleration and speed of the car)...WOW!!

 
Rep Power: 314

No offence intended.
Use your brain! ie: 50 should read 53, ect!
My 17s are a little smaller, but I never look at the speedo any way!

 
Rep Power: 0

u guys are dumb, its common knowledge that having a different sized tire height throws off the speedo, thats y trucks with huge tires are never on the right MPH. So let the Flaming begin on u NOOB, for not knowing something as common as that. Thats 1 of the reasons y people use such low profile tires on 17's and 18's, to retain the stock speed.

 
Rep Power: 314

Gee wiz, gosh golly! And I thought it was to maintain the performance level we wanted! Guess I got a lot to learn. You are the man. Thanks a lot.

 
Rep Power: 0

im askin for it on this one.....


the fact that the speed is different doesnt really bother me. but if it states you are going faster than you actually are isnt it also adding mileage to your vehicle that you actually arent driving or am i way off base on this?

 
Rep Power: 0

on my stock firestones: 185/65/15 top speed was 115-120
on my falken ze512: 205/60/15 top speed was 104?
can someone explain that one please?

 
Rep Power: 293

Farage, you are having the same issue I was having...thus, the very reason why I satarted this thread, but now I do understand it.
As Zzyzx explained, smaller tires than stock give you faster acceleration and lower top speed. Bigger tires than stock give you slower acceleration, but higher top speed.
Using the tire calculator, you are going 5.37% slower than what your speedometer is actually showing. So, say it shows you are going at 70mph, you are actually doing 66.3mph.
I imagine that to get the speedometer to work properly or as close as possible to its factory reading, next time we buy tires, we must play with the measurements on the tire calculator until it gives you the smallest number possible on the speedometer reading % with the new tire.