im planning on 18 inch wheels but have no clue how to understand tire sizes and i wanna know what lowering springs i should get along with that...

any help please

 

Example 295/35/18

295 is the milimeter width of the tire tread. This can sometime be shown in inches but with our cars and tire sizes it usually not.

35 this is the distance (in mm's)between the rim of the wheel and the tire. tread. The lower the number, the less tire is between the wheel and the ground.

18 This is the actual wheel diameter, edge to edge. This is not the width of the wheel.

Is this what you wanted to know.

As for lowering springs...The first thing you need to do is figure out how low you want to go. Then look at springs in that height range. A good comparison is between the Eibach pro-kit and sport line. Pro-kit lowers 1-1 1/2 inches and the sport line 2+ inches, which is very low. Like everything else, beauty is in the eye of the beholder, get what YOU want.

I have the pro kit and have no problems driving around. No scrapes, dents, rubs, bottom out or anything like that.

 

No, middle number is the PERCENT to multiply the width of the tread (the first number) by to get the sidewall height. In the case you mentioned, 295/35/18, the sidewall would be 295mm X 35% = 103.25mm. To get the diameter (height) of the tire, calculate the sidewall height just like we did, multiply it by two, convert it to inches, and add that to the wheel diameter. In the case you mentioned, that's 103.25mm sidewall height X 2 = 206.5mm. Converting to inches, that's 8.13 inches. Adding that to the wheel diameter, you get 26.13 inches.

The stock 235/55 R17's are 27.18 inches in diameter (height), so 295/35 R18's would be slightly smaller. This would make the speedometer inaccurate unless you adjusted it with a tuner. EDIT: actually, it's slightly inaccurate with the stock tires, so 235/35 R18's might make it either less accurate or more accurate. But defiately slightly different. IF the speedo read 60 MPH with the 235/55 R17's, it would read 62.5 MPH with the 295/35 R18's.

Here's an online calculator that will do the math for you: http://www.dakota-truck.net/TIRECALC/tirecalc.html

 

I reffer to these two posts by F1Fan for planning my suspension:

https://mustangforums.com/m_934501/m...tm.htm#1245986

https://mustangforums.com/m_2596309/...tm.htm#2603089