3.3TT I need some summer tire size advice

[Rennokas]

Hi

Just bought a Black GT (EU version), fully loaded. It came with cold climate winter tires Nokian Hakkapeliitta R2 lamelles.

So I am looking for summer tires, probably Michelin Pilot Sport 4. I need advice for deciding on the tire size tho.

Our roads are crap here (in Estonia) and original size 225/45/19 front 255/35/19 back are really harsh.
Would 225/50/19 front 255/40/19 back fit without issues? (would be 3.3% front /3.9% back bigger in diameter)
Or even 225/55/19 front 255/45/19 (6.6% / 7.7% bigger)? (those would probably look weird)

 

[Rennokas]

Or maybe 235/50/19 front 245/45/19 back (easier to find such tires)

 

[MerlintheMad]

I would not mess with OD, per the warnings from the owners manual. If "really harsh" means you are being driven insane by your hard, bumpy, crappy ride, then it seems to me that downsizing the rims and adding more sidewall is the only possible answer: oh, and drive in Comfort Mode at all times.

 

[Bauser]

I down sized to 18's and I find the ride way nicer. See my sig for sizing, I am also thinking about going up to a 245/45r18 front and 275/40r18 on the rear to get a bit more of the stuffed look

 

[Rennokas]

I would not mess with OD, per the warnings from the owners manual. If "really harsh" means you are being driven insane by your hard, bumpy, crappy ride, then it seems to me that downsizing the rims and adding more sidewall is the only possible answer: oh, and drive in Comfort Mode at all times.

Wouldn't say the ride is crappy, its a bit on the firmer side even in comfort mode (and even more so in sport mode).
Its also about not wanting to invest in new rims, just tires. A bit more sidewall helps saving the suspension too.

 

[MerlintheMad]

Wouldn't say the ride is crappy, its a bit on the firmer side even in comfort mode (and even more so in sport mode).
Its also about not wanting to invest in new rims, just tires. A bit more sidewall helps saving the suspension too.

But the OD is paired to the electronics, the monitoring, etc. You can't just make your OD BIGGER without risking trouble or even damage.

 

[turboAWD]

But the OD is paired to the electronics, the monitoring, etc. You can't just make your OD BIGGER without risking trouble or even damage.

Pretty sure a bigger/smaller OD isn't a big deal, as long as it's consistent between front/back. Systems like this usually base things on relative rate of spin / slippage, not absolute speed.

Now, you will throw off the speed sensor, and your speed readings will be a bit off, etc. But I wouldn't think the system would totally freak out if you went 1/2 to 1 inch larger or smaller OD all around. Think about the same tire, new and bald. That's 11/32 on both ends, or 22/32s all around, which is basically 2/3 of an inch bigger when new than bald. Would you expect to damage your car by driving your tires down to 1/11th on nicely paved roads in the summer? Plus, add inflation into the mix and you can probably make another 1/4 inch difference.

 

[MerlintheMad]

Pretty sure a bigger/smaller OD isn't a big deal, as long as it's consistent between front/back. Systems like this usually base things on relative rate of spin / slippage, not absolute speed.

Now, you will throw off the speed sensor, and your speed readings will be a bit off, etc. But I wouldn't think the system would totally freak out if you went 1/2 to 1 inch larger or smaller OD all around. Think about the same tire, new and bald. That's 11/32 on both ends, or 22/32s all around, which is basically 2/3 of an inch bigger when new than bald. Would you expect to damage your car by driving your tires down to 1/11th on nicely paved roads in the summer? Plus, add inflation into the mix and you can probably make another 1/4 inch difference.

The OE tires are the acceptable range from new to worn. Starting with a bigger OD than the OE tires is asking for issues. I just don't see the sense in ignoring the advice in the manual. What's the point? Just a "better look"?

 

[turboAWD]

The OE tires are the acceptable range from new to worn. Starting with a bigger OD than the OE tires is asking for issues. I just don't see the sense in ignoring the advice in the manual. What's the point? Just a "better look"?

Your do realize that between different brands, same size, OD will vary as well? Does that mean you can only ever run the OEM tires? Is OD the same between 18" and 19"? Probably some variance there, although not that much.

Sometimes I think you worry a little too much..

 

[MerlintheMad]

Your do realize that between different brands, same size, OD will vary as well? Does that mean you can only ever run the OEM tires? Is OD the same between 18" and 19"? Probably some variance there, although not that much.

No, I didn't know that. The manual does recommend staying with the OEM tires and wheels. I'm sure they are emphasizing making sure the OD stays the same: any other tire or aftermarket rims should be picked to do that as closely as possible.

Sometimes I think you worry a little too much..

Probably. But it has kept me from ruining my stuff over the years.

 

[Rennokas]

The OE tires are the acceptable range from new to worn. Starting with a bigger OD than the OE tires is asking for issues. I just don't see the sense in ignoring the advice in the manual. What's the point? Just a "better look"?

Better look, softer daily driving and saves suspension on bad roads. Depending on the region, some sizes are hard to come by also.
Gonna try out 225/45/19 front 255/40/19 back I guess. Fills the wheel wells 11mm front and 13mm back compared to the original size.

 

[Manaz]

On a RWD, different OD front to rear won't really matter, as long as you have a consistent I'd across a given axle. Yes, you may upset the speedometer calibration, but that's about it - the car largely doesn't care otherwise how many rpm the tyres are doing at a given speed.

The Kia AWD system also allows for a degree of variation between front and rear OD, as evidenced by Canadian vehicles with staggered fitments and AWD. But I would try to keep front to rear as close as possible, just to be sure (some variation likely doesn't jump to even high single-digit percentages of variation front to rear before damage occurs).