Tire Size Question

Ohmess

Ohmess

I wanna DRIVE!
Site Donor $
Messages
5,262
Reaction score
3,154
Location
Aiken, SC
What are the disadvantages with going with a tire that is slightly smaller than the stock tire? I know my speedo will be off. If I have this right, it will actually be telling me I am going faster than I am traveling because smaller wheels need to spin faster at any given speed.

(Assuming my wheels arrive as expected), I am looking at a set of 225/50 15s, and they are 23.9" high, which is 3.3% smaller than the stock tire.
 
Use this chart for proper tire sizes.

OEM tire Size: 195/70/14 – dia. 24.7”, 77.7” circ, rev / mile = 815
Substitutes: 205/60/15 – dia. 24.7”, 77.6” circ, rev / mile = 817
Substitutes: 225/55/15 – dia. 24.7”, 77.7” circ, rev / mile = 815
Substitutes: 205/55/16 – dia. 24.9”, 78.2” circ, rev / mile = 811
Substitutes: 225/50/16 – dia. 24.9” 78.1” circ, rev / mile = 811
Substitutes: 245/40/17 – dia. 24.7”, 77.6” circ, rev / mile = 816
 
For 15" rims? If so, I am running 215/60/15 which are 2% bigger diameter.

They are pretty fat so better have front fenders rolled. I am considering keeping the backs and replacing the fronts with 205/60's for a little more room.

205/60/15's are very close to same diameter as stock 195/70/14.
 
Yes I rolled my fenders, especially since I have lowering springs on them. 225's will definitely stick out past the fenders with my rims (I have negative camber plates and my 215 front tires barely stick out, another reason I am considering 205's.

But I suppose that also is determined by the offset amount compared to my OZ alpinas, I don't know what their measurement is so if you have a more favorable offset then maybe the wider tire wouldnt be a problem.

Either way I'd roll the fenders, a bent fender wheel well really sucks.

Ohmess said:
Thanks Andrew -- Your chart is helpful, as is this: http://tire-size-conversion.com/tire-size-calculator/

Steve -- when you say they are pretty fat, are you referring to your tires at 8.46" or the ones I reference, which are 8.86"

Did you feel the need to roll your fenders for the 215/60/15s?
Click to expand...
 
Damn, one more thing to add to the list of things to do.

What tires are you running, and how do you like them?
 
I have Michelin MXV4's. I wanted a high quality touring tire and these fit the bill.

I'd love to have a vintage repro tire but I chose to spend the coin elsewhere.
 
michelin pilot sport 3 225/45/17 with rolled fenders and camber plates, awesome tyre but they don't do anything smaller than 17inch so not much help to you.
The only rubbing I get is at the back of the wheel well when I have a lot of lock on, turning into driveways etc
 
kasbatts said:
michelin pilot sport 3 225/45/17 with rolled fenders and camber plates, awesome tyre but they don't do anything smaller than 17inch so not much help to you.
The only rubbing I get is at the back of the wheel well when I have a lot of lock on, turning into driveways etc
Click to expand...

Well, yes that is actually my first choice. The last three sets of tires on my e39 sedan have been from that line. Great tires, and if they came in 15s my decision would be easy.

Unfortunately, I've been running Michelins for so long I am rather lost having to look at other tires.
 
14" wheels

I am committed to keeping the 14"x7" Alpina wheels. This is a given.

Currently, the coupe has 10 year old Michelin Pilot 225x60x14 tires.
The winter plan is to buy new tires and to refurb the wheels.

I could simply buy 4 new BFG 225x60x14 tires but am wondering what (if anything) would be the benefit of using 215x60x14 on the front.

The diameter of the 225's is nearly identical (-0.4%)
The diameter of the 215's is a bit further off (-2%)

I will always be going a bit slower than my speedometer reads.
 
It seems that I don't have this problem. Every time I get stopped by law enforcement, they tell me I was going much faster than my speedometer!
 
Stan,

a smaller front diameter / width isn't going to change the speed as that is measured by the rear wheels ... the 215/60 would only make a difference if it was on the rear

s

Stan said:
I am committed to keeping the 14"x7" Alpina wheels. This is a given.

Currently, the coupe has 10 year old Michelin Pilot 225x60x14 tires.
The winter plan is to buy new tires and to refurb the wheels.

I could simply buy 4 new BFG 225x60x14 tires but am wondering what (if anything) would be the benefit of using 215x60x14 on the front.

The diameter of the 225's is nearly identical (-0.4%)
The diameter of the 215's is a bit further off (-2%)

I will always be going a bit slower than my speedometer reads.
Click to expand...
 
You must log in or register to reply here.
Back
Top