Speedometer calibration?

[Briken]

Will need my first new set of tires in the next few months and wanted to go bigger. The contact patch for the 255 rear seems really pushed in compared to where the sidewall is. I'm awd btw. A dealer near my friend has had this car listed for over a year now and was curious if I went to 245/35/19 and 385/35/19 on my scorpion wheels, which I'm 99% sure are the same size as normal gt2 wheels, could I get the speedometer recalibrated so I don't have to worry about the speed difference? I saw a lot of people are running 285/30, is that more for looks?

It wont let me post the link to the car but it's Courage Kia in north carolina for 72k (lol)

 

[Briken]

I was just messing around with the rim / tire calculator and saw that 245/30/19 front and 285/ 30/19 rear would be 59 and 59.3 mph at 60. So probably wouldn't need to mess with the speedometer really. I assume the awd system would allow for that difference in speed?

 

[SRV]

This is what you should run for AWD:

245/35/19 - front
285/30/19 - rear

Put that into the calculator to make sure.

 

[Briken]

That results in a front wheel speed of 61.3. Why 35 for the front?

Rim & Tire Size Calculator. Custom Offsets

Tire Tech Information - The Wheel Fitment, Tyre Stretch, Rolling Radius and Speedometer Error Calculator. Play with specs, try different settings, compare results

www.wheel-size.com

 

[Redleg94]

That results in a front wheel speed of 61.3. Why 35 for the front?

Rim & Tire Size Calculator. Custom Offsets

Tire Tech Information - The Wheel Fitment, Tyre Stretch, Rolling Radius and Speedometer Error Calculator. Play with specs, try different settings, compare results

www.wheel-size.com

I see your mistake. The stock front tire is a 225/40, not the 225/35 that you have in the calculator. The 245/35 pairs nicely with a 285/30 rear.

 

[Briken]

I see your mistake. The stock front tire is a 225/40, not the 225/35 that you have in the calculator. The 245/35 pairs nicely with a 285/30 rear.

Yooo thank you! I didn't realize they were different sidewalls stock. Thank you so much! Any idea why they used such small width on a rear that can hold 30mm more? mpg?

 

[MerlintheMad]

Any idea why they used such small width on a rear that can hold 30mm more? mpg?

255 wide on 8.5" rim is not small. According to this chart 255 is the "max width" recommended for the OEM rim.

 

[Redleg94]

255 wide on 8.5" rim is not small. According to this chart 255 is the "max width" recommended for the OEM rim.
View attachment 76247

I guess the real question then, is why not have wider wheels in the first place? We know that a 295 on a 10.5" with the proper offset fits reliably under the fenders, so why not offer that from the factory?

 

[MerlintheMad]

I guess the real question then, is why not have wider wheels in the first place? We know that a 295 on a 10.5" with the proper offset fits reliably under the fenders, so why not offer that from the factory?

Saving money. Kia went with the minimum sized tires/rims to achieve the stated (concept) goal of a high performing Gran Turismo. 99% of all "spirited" drivers (like myself) find the 225/255 Michelin PS4(S) more than adequate. Even the 18" wheels with the A/S tires satisfy the goal, the Michelin summer tires are just that much better.

If I were ever to go wider, I'd go with what I've seen (reading all the posts on this topic for years) as the most common upgrade: a set of 9" and 10.5" wheels and 245/35 and 285/30 tires.

 

[Briken]

Saving money. Kia went with the minimum sized tires/rims to achieve the stated (concept) goal of a high performing Gran Turismo. 99% of all "spirited" drivers (like myself) find the 225/255 Michelin PS4(S) more than adequate. Even the 18" wheels with the A/S tires satisfy the goal, the Michelin summer tires are just that much better.

If I were ever to go wider, I'd go with what I've seen (reading all the posts on this topic for years) as the most common upgrade: a set of 9" and 10.5" wheels and 245/35 and 285/30 tires.

So I ended up getting the a/s, I didn't even know it was an option but was glad because I was working in VA in winter. But mannnnn is there a difference. Had the ps4s on my TTS and miata and it was just grip for days.

 

[Briken]

I guess the real question then, is why not have wider wheels in the first place? We know that a 295 on a 10.5" with the proper offset fits reliably under the fenders, so why not offer that from the factory?

Hey, I saw in another post that people are doing 255-35-19 and 295-30-19. I've got the stock scorpion wheels. I assume it will fit from what I've read but why wouldn't people buy the bigger tires vs the ones weve been talking about?

 

[Redleg94]

Hey, I saw in another post that people are doing 255-35-19 and 295-30-19. I've got the stock scorpion wheels. I assume it will fit from what I've read but why wouldn't people buy the bigger tires vs the ones weve been talking about?

If you want to go 295 in the rear, you need to go with at least a 10" wide wheel, more likely a 10.5" or 11"

 

[Briken]

If you want to go 295 in the rear, you need to go with at least a 10" wide wheel, more likely a 10.5" or 11"

Gotcha, but the 245/35 and 285/30 will fit on stock 19s?

 

[Redleg94]

Gotcha, but the 245/35 and 285/30 will fit on stock 19s?

I don't know if I would go with an 8.5 for a 285-section tire, the attached shows a 9.5 minimum: 285/30R19 Tires

 

[BDPershing]

So is there a way to change wheel calibration?

 

[G70LEbyAdoom]

So is there a way to change wheel calibration?

No, I've talked to 4 different dealers and have a friend who is a shop foreman and a master tech at a kia dealer, No dice.

 

[str8bizns]

If you want to go 295 in the rear, you need to go with at least a 10" wide wheel, more likely a 10.5" or 11"

295/30/19 on 9.5” wheel

 

[Redleg94]

295/30/19 on 9.5” wheel

That is interesting. Everything that I've seen for recommended wheel width has a 285 as the widest tire that will fit on a 9.5" wheel. Have you run these yet? How do they fit on the car? Offset of the wheel? Any issues? I've you've been successful then I just may go that way next time.

 

[str8bizns]

That is interesting. Everything that I've seen for recommended wheel width has a 285 as the widest tire that will fit on a 9.5" wheel. Have you run these yet? How do they fit on the car? Offset of the wheel? Any issues? I've you've been successful then I just may go that way next time.

 

[str8bizns]

I went through a month of obsessing over the tire sizes and couldn’t get anyone to answer. I google for images and only saw one guy with a Porsche running 295 on a 9.5” wheel. Nothing but negative comments. I had 285 on there but I saw that I knew I could run the 295’s well after going through the cheap tires I had in there in less than 5 months, I looked for 285’s and couldn’t find any for less than $300 and I needed them yesterday as I hadn’t noticed I was running on bald tires. I ordered them last night and today I mounted them and I’m I. The car right now enjoying the shit out of them. I’m dropped on Eibach’s. No rubbing no issues. Offset +40