Hi,

This may sound like a dumb question, but how much would my wheel gap INCREASE between a:


225/45/18 and 225/40/18 ???


and also, how much difference between

215/50/17 and 225/4-/18

and also if you can..

205/55/16 and 215/50/17

and 205/55/16 and 225/40/18


the car is at STOCK height.

thanks

 

calling EricL............

 

22.5 mm (almost one inch). for 225 (45 to 40 series).
215/50-17 is pretty close to 225/40-18
205/60-16 is close to 215/50-17 so 205/55 would be app 20mm less diameter (or more wheel gap).

 

225/45/18

225mm*.45*2+18"
8.85 inch*.45*2+18

25.97 inch tall total

225/40/18

225mm*.40*2+18"
8.85 inch*.40*2+18

25.08 inch tall total


(this is all based on whether the tiers specs are accurate

 

how did you get those numbers?

how close would 225/40/18 be to stock?

 

225/50 -17

the mm in width/ the % of the width in height - the wheel diameter in inches.

width = 225 mm.
side wall height = 112.5 mm.

 

THANKYOU!!

thats all i need to know

 

ok so all these are correct sidewall numbers?

225/40/18=90
225/45/18=101.25
215/45/18=96.75
215/50/17=107.5
205/55/16=112.75

 

Theoretically, yes. All manufacturers vary a bit on their measurments, though

 

use this site http://www.miata.net/garage/tirecalc.html

 

that is low profile.the lower the profile the tire is.the better handling u are going to get at conering..and the wider tire u get.the better handing u will get too..it is physic principle...if u want an object to be stable..first increase the base area.and second.lower the center the gravity..hope this might help u

 

okay i cant decide...

I have 18x7 rims with 42 offset,

I wanna do a comptech Drop and...


225/40/18
or
235/40/18


my main concern is RUBBING...dont forget, I'm on a SEVEN inch wheel, not 7.5

 

If you change the wheels, you have to keep the stock diameter,

17" = 50 series

18" = 40 series

19" = 35 series

.................I THINK?????????

 

I would defintely go 225-40/18 if you are planning on lowering, especially with the +42 offset. I just swapped out my 235-45/17 Toyo Proxes for 225-45/17 on my 17x8 wheels because of minor rubbing on the inside top of both front wheel wells (I am Comptech-lowered also).

 

but i dont understand, doesnt the fact that your on a 8" wheel make any difference?

I am going on a 7" wheel...

does the width of the rim not matter?

 

I am no expert at this, but I think wheel width certainly does matter. However, with any given wheel width you have some lattitude to select tires of different width.

I believe most all tire sizes have an "optimal" and "acceptable" wheel width specified by the manufacturer. For the 235-45/17 Toyos I first bought, the "optimal" width is shown as 8", but a wheel width as low as 7.5 inches and as high as 9.0 inches is shown as acceptable. For the 225-45/17 Toyos I recently bought, the "optimal" width is 7.5", the minimum width is 7", and the maximum is 8.5.

Check out the Toyo website reference below, that is what I based my information above on (would expect it may be different for each tire manufacturer).

http://www.toyo.com/tires/tire_specsheet.cfm?id=2

 

go to www.tirerack.com they have info on everying you want.

 

Tirerack has some good info, mostly on wheel/tire combinations that THEY deem are acceptable for your car (which happens to exclude a lot of choices that would otherwise work fine). And try to get any specifics about wheel offset from their site or their telephone representatives...it's impossible.

 

There is a TON of confusion about what is the "optimal" rim size for a tire. Unfortunately, there are times when the measuring rim size (the number usually in the center and/or highlighted) is not the same as the optimal rim size.

The “Measuring Rim Size” denotes the rim width used by the manufacturer to test and provide all of the "data" for a given tire size/make (there are always going to be some exceptions). People assume that the measuring rim is the "optimal" rim size for the tire; in a number of cases, that is probably true. However, there are times when people who race for a living will use slightly wider or narrower rims for improved performance based on track times, etc…

For example, when I had my 235/45-17 Toyos on the 7" wide stock rims, they seemed to grip the road just as well as they do on the 8" wide SSR wheels (I bought the wheels for lower unsprung weight/lower rotational inertia). The tires have a measuring rim size of 8 inches (with minimum at 7.5" and max at 9")

 

Caveat:


The 225-40/18s not produced by Toyo, Nitto, and a few others only have a load rating of 88. IMO, that is too low.

The Toyo and Nittos have a 92 load rating in the 225-40/18 (and a few other tire makers have a 92 rating -- check first).

A 225/45-18 might be a better choice when the 225/40-18's load rating (for that particular make and brand of tire) is only 88). (I am assuming that the tire is available in both sizes and that is not always the case.)

 

17" --> 215/50-17 & 225/45-17 & 235/45-17 & 245/40-17 (depending)
18" --> 225/40-18 & 225/45-18 & 235/40-18 (225/40-18 - watch the load rating)
19" --> 235/35-19


(There are other sizes and options that I'm probably missing, but these represent the bulk of the sizes that have been used and work for members here. Some sizes will only work with non-lowered cars, certain offset, wheel widths, etc)