Speedometer calibration

[Kalter]

Hey all, sorry if this question has been asked before, but I can't find an actual answer on the forum search or on Google.

I'd like to switch to wider tires. 215/40R17 would be the evident choice as the difference with stock is minimal and there are good choice in that size, but I'd like wider, so I'm looking at 225. Looking at tirerack.com and 225/40R17 is basically nothing (except two slicks) and a smaller ratio doesn't exist.

Which leads me to 225/45R17. I believe I saw a few around here that are running in those size?

I don't care about rubbing, as long as it doesn't rub in a straight line and I'll have the fender rolled if necessary, but are you guys running with the speedometer this off?

I'd like to know more precisely, is it possible for a tuner to change the speedometer calibration through the Cobb AP?

225/45R17 is 6% off, that's quite a bit for me, but I want a wider track!

 

[Xaendeau]

There is a parameter in the accessport. Something like revs per mile on the tire. Should be set to 800-something, you can see it in the logged parameters. Don't think you can modify it on the stock tunes, but you can get a tuner to fiddle with the numbers.

Also, 225/45R17...might rub a lot. Depends on the tire, check the forum search in the tire section. Might be stickied. IIRC someone tried it and it didn't work, but could be wrong. I am stepping down to 15x8 on 225/45R15, should fit a bit better.

 

[Kalter]

There is a parameter in the accessport. Something like revs per mile on the tire. Should be set to 800-something, you can see it in the logged parameters. Don't think you can modify it on the stock tunes, but you can get a tuner to fiddle with the numbers.

Also, 225/45R17...might rub a lot. Depends on the tire, check the forum search in the tire section. Might be stickied. IIRC someone tried it and it didn't work, but could be wrong. I am stepping down to 15x8 on 225/45R15, should fit a bit better.

Alright, so what you're telling me is that if I'm not ready to invest in some rims and body work, I should limit myself to 215/40R17.

What sucks is that 225/45 are the same price and sometimes cheaper than 215/40...

Sent from my ONEPLUS A3000 using Tapatalk

 

[nickstewartroc]

Be aware you might not be able to change the tire size through the tuner, I would check with whoever you are tuned through before buying. It may be possible to change it using ForScan however

 

[alexrex20]

my cousin runs 215/45-17 on his FiST and it rubs in the rear on full compression, so only going over speed bumps and such. his speedo is off a bit but not by much. 225/45 is wider and taller so your rubbing may be substantial. i'd go to the tire shop first and have them test fit to see if they rub.

 

[Truth in Ruin]

There is a parameter in the accessport. Something like revs per mile on the tire. Should be set to 800-something, you can see it in the logged parameters. Don't think you can modify it on the stock tunes, but you can get a tuner to fiddle with the numbers.

Also, 225/45R17...might rub a lot. Depends on the tire, check the forum search in the tire section. Might be stickied. IIRC someone tried it and it didn't work, but could be wrong. I am stepping down to 15x8 on 225/45R15, should fit a bit better.

Are you talking about the Rival S 1.5 225/45/15 tires? If so, I’d like to hear what you think of them, how they fit, etc.

 

[TomCat]

FWIW, I have had no rubbing issues with 215/45/17 on stock suspension and wheels.
Tires are General A/S.
Near as I can tell, the speedo is about 5% off but I just live with it.

 

[Xaendeau]

Are you talking about the Rival S 1.5 225/45/15 tires? If so, I’d like to hear what you think of them, how they fit, etc.

Will do, should be when the weather warms up a bit in the deep south. Have a few 1/16ths left before I hit the wear bars on my current tires.

 

[rallytaff]

Might be a stupid question, but wouldn't your gas mileage suffer a little by going to smaller wheels? Just asking.