tires: difference zr and r

[justnobody]

my tire size is 225 40 zr18, whats the difference between that and lets say a 225 40 r18, because i want to buy tires for the the winter while keeping the same R1 racing rims, would that still be able to work? basically i just want to get rid of my low profile tires and get something thats all seasoned that will still fit the rim. idk anything bout this stuff as you can tell ..

 

[95blackGsTurbo]

ZR and R are the speed ratings. You don' really need either because you will never go 168+. The sidewall of the tire is determined by the 2nd number. You will need to change the 40 profile to a 45 or 50 depending on how much lower your car is than stock. With a 225 you are pretty much stuck with a low profile tires.

 

[DGajre777]

The R in ZR means RADIAL
http://www.tirerack.com/tires/tiretech/techpage.jsp?techid=46

Beginning in 1991, the speed symbol denoting a fixed maximum speed capability of new tires must be shown only in the speed rating portion of the tire's service description, such as 225/50R16 89S. The most common tire speed rating symbols, maximum speeds and typical applications are shown below:
M 81 mph 130 km/h
N 87 mph 140km/h Temporary Spare Tires
P 93 mph 150 km/h
Q 99 mph 160 km/h Studless & Studdable Winter Tires
R 106 mph 170 km/h H.D. Light Truck Tires
S 112 mph 180 km/h Family Sedans & Vans
T 118 mph 190 km/h Family Sedans & Vans
U 124 mph 200 km/h
H 130 mph 210 km/h Sport Sedans & Coupes
V 149 mph 240 km/h Sport Sedans, Coupes & Sports Cars

When Z-speed rated tires were first introduced, they were thought to reflect the highest tire speed rating that would ever be required, in excess of 240 km/h or 149 mph. While Z-speed rated tires are capable of speeds in excess of 149 mph, how far above 149 mph was not identified. That ultimately caused the automotive industry to add W- and Y-speed ratings to identify the tires that meet the needs of new vehicles that have extremely high top-speed capabilities.
W 168 mph 270 km/h Exotic Sports Cars
Y 186 mph 300 km/h Exotic Sports Cars

While a Z-speed rating still often appears in the tire size designation of these tires, such as 225/50ZR16 91W, the Z in the size signifies a maximum speed capability in excess of 149 mph, 240 km/h; the W in the service description indicates the tire's 168 mph, 270 km/h maximum speed.

http://www.tirerack.com/tires/tiretech/techpage.jsp?techid=35

More reading stuff here - http://www.tirerack.com/tires/tiretech/tiretech.jsp

 

[snowborder714]

ZR and R are the speed ratings. You don' really need either because you will never go 168+.

Actually, on the Z is the speed rating. The R is for the the internal construction type. Here is what the R means:

The R in the P225/50R16 91S size identifies that the tire has a Radial construction in which the tire's body plies "radiate" out from the imaginary center of the wheel. Radial tires are by far the most popular type of tire today representing over 98% of all tires sold.

You will need to change the 40 profile to a 45 or 50 depending on how much lower your car is than stock.

I think you mean 35 or 30 (instead of 45 or 50). I don't think you can fit anything bigger than a 40 on 18" rims and stock ride height without the tires rubbing. You'd have to get something with a smaller sidewall if it's lowered.

Here's a good link to learn about the tire markings - http://www.tirerack.com/tires/tiretech/techpage.jsp?techid=46&currentpage=37

And look at different articles using the drop down box at the top.

 

[justnobody]

oh wow .. thanks for all that info

 

[95blackGsTurbo]

He wants more of a sidewall so he will need to go from a 40 to a 45 or 50 depending on how low his car sits. I have put 225/55/18's on a stock height 2g and they fit fine. Rode a little high but that's what you gotta do. If you want more of a sidewall for the winter I recommend just buying a cheap set of stock rims/tires and running those in the winter months.

 

[snowborder714]

Wow, everything I've been told and read said that you can't put that big of a sidewall on 18's without rub. Interesting.

 

[oldman]

oh wow .. thanks for all that info

Please use proper grammar, punctuation and caps in tech forums.