Ram Air Formula

Ok, I did a search and studied for well over an hour to make sure I did this correctly. I just really would like verification on this before I spend lots of money.

I'm putting new rims on a C5 vert. The rims are 18x9.5 front and 19x10.5 rear. I'm looking at BFG KDW NT tires front and rear. Front size is 275/35/18. Rear is 295/35/19. Will my TC be happy with these sizes?

By my calculations, the overall diameter difference between the front and rear will be 1.6 inches. Doing the same calculations to the factory tires, I get a 3.2 inches difference between front and rear. What I am finding is that so long as I stay greater than a 1/2 inch difference I should be fine. Since 1.6 is between 1/2 and 3.2, I figure I should be fine. Will I?

Thanks

steve8

I don't understand your numbers, but the sizes you posted will work.
Plug anything you want into this calculator.


http://www.miata.net/garage/tirecalc.html

Ram Air Formula

I got the numbers by multiplying the second number(aspect ratio) by the first(width in mm) then multiplying by two(since there are two sidewalls to the overall diameter) and adding that number to the rim diameter.

So you're saying they will work because the difference between them and the stock sizes is minimal according to that calculator?

Thanks for the link.

blacksedan87

Your selected sizes will work - simply as long as the overall diameter of the back tire is larger than the front, meaning the back tire will spin slower than the front - the traction control system will not read the condition as wheel spin.

The front tires have an overall diameter of 25.58" and the backs are 27.13", meaning that the fronts will have 788.47 revs per mile and the backs will have 743.39 revs per mile.

Here's what I used to calculate this -

http://www.discounttire.com/dtcs/infoTireMath.dos

0JPM@AutoBuffs

The following sizes will be fine and no speedo issues.

Front: 275 / 35 / 18
Rear: 305 / 30 / 19


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Blue 92

I like this tire calc site:

http://www.rims-n-tires.com/rt_specs.jsp

Let's you do two at once and compare side by side.

Ram Air Formula

this was part of my reason for wanting verification. My measurements did not match my calculations of the factory tires on the car. I guess I need to double check my math.

Thanks for all the help guys.

Ram Air Formula

This was another part of it. I used discounttiredirect.com for searching out tires. The sizes they recommended did not have a matching front and back in either the BFG KDW NT or Kuhmo Ecsta MXs, the two tires I am interested in using. I knew from experience I could go wider to get a matching front and rear and still fit on the rim correctly but I was a little uncertain about the traction control. I wish the KDW could eb had in a 305 as that would be even more width. Thank you for the reply.

These are the NTs http://www.discounttiredirect.com/di...il.do?pc=38545
They look like the KDW 2s found on tirerack.com to me
http://www.tirerack.com/tires/tires....ce+T%2FA+KDW+2
These are meaty looking tires. I'll need all the traction I can get too.

FactoryRaceCar

Your selected tire sizes will work with your 18 and 19 wheels. I ran 275/35/18 and 295/35/19 on 18X9.5 front and 19X10.5 rear IForged wheels in 2004 without any problems with TC or AH.

Ram Air Formula

thanks for the excellent information everyone, I greatly appreciate it.