Whipple, Tire Size Changes, Tune needed?

[frostysteven]

Would I need to retune my whipple if I get new tire sizes? I'm looking at swapping tires to a larger tire than my base 275. The only real options I see are to upgrade to 20-inch rims from my 19-inch rims.

Current setup 275/40/R19 (which I would like to keep for winter use)

Summer set up? 315/30/R20. From what I see, the change in actual diameter is very small, leading to the question, would I need to retune the whipple with the flare tool?

Sponsored

 

[robvas]

No

 

[Billycar11]

the whipple tuner has built in tire size changer i believe
or you could just use forscan

 

[Q6543]

Yeah, you can do it with the tomahawk iirc.
I wouldn’t care but whatever, adjust if you need to.

 

[schmeky7]

No, number 2.

 

[Ken H.]

Beware. Your summer setup may cause you to lose Pre-collision Assist & cruise control functions. It did with me. I would recommend trying to stay with stock size wheels (19s) & just get tires that are similar diameter to your stock tires. These computer troubles are killing me.

 

[frostysteven]

Beware. Your summer setup may cause you to lose Pre-collision Assist & cruise control functions. It did with me. I would recommend trying to stay with stock size wheels (19s) & just get tires that are similar diameter to your stock tires. These computer troubles are killing me.

The diameter is less then 1% off, so hopefullly it shouldnt? What percent off are yours?

I appreciate the warning.

The problem with stock size wheels is I cant get to 315 size on 19's and keep the same diameter as they dont really make 315/40(or35)/ R19

 

[Ken H.]

The diameter is less then 1% off, so hopefullly it shouldnt? What percent off are yours?

I appreciate the warning.

The problem with stock size wheels is I cant get to 315 size on 19's and keep the same diameter as they dont really make 315/40(or35)/ R19

I calculated it in past. Don’t remember exactly but it was outside 3%. Put stock 19s back on. Had it recalibrated. Then put smaller fronts on that are within 3% & problem recurred.
Front : Pirelli 305/30/19 stock; tried Michelin PS AS 285/35/20 then 285/30/20 (only 0.4” taller than stock) if my memory is correct.
Rear: Pirelli 315/30/19 stock. Then Michelin PS AS 305/35/20 (still on, didn’t change them).
I’m not sure if I need to go to 275’s front to get even closer to stock diameter &/or 295s rear to get within 3% on the rear. I’m very confused & frustrated with the whole thing. I’m so used to cruise control functions that I can’t drive it in a long trip to NC/FL. Tried once. My gas pedal leg just not conditioned for that after all these years. Totally spoiled with creature comforts.
I think I’m going to try the Goodyear AS 19s that someone posted. They come in 305 & 315 like the stock Pirellis

 

[tastetickles]

Only huge tire circumference changes matter. This is especially true for automatics because it affects shift point preprogrammed into the transmission control unit. Have a look at forscan settings as well, change the tire size to the one closest in the drop down list and then adjust your afe bias too in the diagnostic mode for the most accurate mpg reading in that matters. Note i haven't got my mustang yet but thats what i did on my Focus RS and things i learn from upsizing in the Jeep community.

 

[frostysteven]

I calculated it in past. Don’t remember exactly but it was outside 3%. Put stock 19s back on. Had it recalibrated. Then put smaller fronts on that are within 3% & problem recurred.
Front : Pirelli 305/30/19 stock; tried Michelin PS AS 285/35/20 then 285/30/20 (only 0.4” taller than stock) if my memory is correct.
Rear: Pirelli 315/30/19 stock. Then Michelin PS AS 305/35/20 (still on, didn’t change them).
I’m not sure if I need to go to 275’s front to get even closer to stock diameter &/or 295s rear to get within 3% on the rear. I’m very confused & frustrated with the whole thing. I’m so used to cruise control functions that I can’t drive it in a long trip to NC/FL. Tried once. My gas pedal leg just not conditioned for that after all these years. Totally spoiled with creature comforts.
I think I’m going to try the Goodyear AS 19s that someone posted. They come in 305 & 315 like the stock Pirellis

Yeah, cruise control is a must for me to. I think the computer mainly uses rear size for speed and adustments. I could be wrong (just something i read before trying to plan my journey), sorry changing front probably didnt do so much (edit, just read your height post guess its a combo for the adaptive cruise).

What I read is the total diameter matters more then width (although width will make small changes changes in diameter.)

I found your old post, and yours were 7% off? As you started on a low tread wall at 30/R19. My main goal is just to get wider tires to put down power better. I started at 40/R19. So going to a 20 is the only way I can use michillen and keep my same diameter; is to go to 20s. If I got the 19s on michillen 30/R19 my diameter would be to small.

Mine should be close diameter for both rear and front to original within 1%.

Sponsored