Just curious. Same width, almost 4% taller than the stock 235/45/18. Would add about half an inch of clearance. Probably hurts aerodynamics and mpg a little, but might help curb rash, and also let the car stay in gear mode at 2 or 3 mph higher speed. I doubt clearance in the wheelwell would be a problem, but it would cut it down. You would also get a few more miles out of tires between changes, I’d think. Of course, you get the speedometer and odometer reading 4% low, so you would want to be a little more careful not exceeding speed limits enough to attract attention. I’m sure it would soften handling with the additional sidewall and resulting flex, but I don’t normally stress the car too much in curves. Still, that might be less than desirable. I think it would make our computer overly optimistic calculated mpg be closer to accurate (should cut the 10% error down to 6%). Really just curious if anyone has done this or spent any time thinking about it.
I’m not, and don’t plan to. I’ve had the car in EDM up to 85mph. Don’t know what max speed is in EDM, but I don’t really see a need to have it stay in EDM for a few more mph. More likely, it wouldn’t engage until a higher actual speed, perhaps 47 rather than 45. EDM operates within a very narrow window of torque. Different size tires will change the final gearing, which will have an impact on torque. The car may, or may not, be less likely to engage EDM with larger circumference tires. A 50,000 mile tire is a 50,000 mile tire, regardless of tire diameter/circumference. There’s no guarantee that the tire would last for more miles. Driving habits play a more significant role. Calculating mpg is best done using miles driven (on OEM tires) and fuel consumed, but that is only accurate if all the miles were driven in HV mode. On the rare occasion that we actually use gas, some of those miles are typically driven in EV mode, so it would be necessary to subtract the EV miles from the HV miles to get an accurate calculation. Not the most productive use of one’s time, in my opinion. Most importantly, you’d be signing an inaccurate odometer reading upon sale of the vehicle, which would surely lead to a pants down spanking.
@Landshark, thanks for the reply. I've never watched the EDM mode at higher speeds. I was under the assumption that it would drop out at less than 85 mph, I would have guessed more like 70. You are right that it would increase the speed at which it would engage by 4%, but I'd think the range at which it is in effect would go up 4%, so you should gain more on the high end than on the low end, but as you say torque may trump speed in it's operation, and if so, I am not sure anything would change in when it engages. You could also be right about the tire life. I was thinking that for two of the same tires (Michelin Energy Saver A/S, for example) the larger tire would start with the same composition and tread depth as the smaller tire and should run longer if less revolutions per mile. Tire manufacturers may take this into account and slightly decrease the starting tread depth of larger tires. Regardless 4% isn't a lot of extra life, only 1,000 miles or so for the life I get from most tires. I agree that MPG is painful to even talk about with a PHEV. I probably burn more gas than you do, about 1/3 of my driving is gas. I do keep up with gasoline purchased for the car, mostly to back into EV miles, and just assume gasoline mpg at 40. It's still kind of nice on trips to see what the computer mpg looks like. As to the last one, I don't plan on selling this vehicle until it drops (either wrecked or dies), I doubt the mileage will impact the sale value much. I've got a 2002 Tahoe that I bought new in 2002 and has had 2% larger diameter tires on it since the first set of tires. On that vehicle, it helps with mpg (since it helps engine rpm to cruise at slightly lower value on the highway). I've got nearly 230k miles on it now, which means the odometer is off by about 4,000 miles. I doubt anyone would care if I told them when I traded it in. I have been known to curb rash my wheels. The slightly taller tire might help with this. It is a pain to sand them down and repaint the damaged areas when I do this. Yes, it would be better if I was just a more careful driver and alert driver (guilty as charged). It did also dawn on me that this would add 4% to the top end of the car, but I doubt any of us hit 100 mph on a regular basis, so 104 mph isn't much of a perk. I have already purchased the next set of tires for the car (235/45/18) and they are in the garage, so its doubtful I will move to the larger size, but I was curious what others would think. Again, I haven't researched to make sure that the loss of 1/2 inch of clearance inside the wheelwell isn't a problem (seems most internet tire recommendations are to increase no more than 3%, this is at 3.8%). It'd suck for it to bottom out on a bump and make contact damaging something (tire or car). Thanks again for your reply.
Someone should try this size just on the rear. I've always thought the wheel pants make the rear appear to slope down. Hopping up the rear with the 50s might counter that appearance. Also would assume no impact to odometer if just on rear. Rotating on the diagonal would no longer be appropriate, though.
Imagine the impact on those carefully calibrated laser beam emitters and other sensors on the front. And what would it do to those dismal headlights that some find to be inadequate?
If I did the math right, 1/2 inch over 110 inches (wheelbase is 108) is a decrease in aim of 1/4 degree (0.25 degrees). At 100 ft, the headlights would shine about 5 inches lower. Probably not very noticeable.
Did you read the thread about the windshield installer at Safelite who asked one of our members to bring the car in with about 3.5 gallons of gas in the 7 gallon tank, so that the camera could be properly calibrated?
I guess my worry would be the added flex on the sidewalls. These cars are pretty heavy, and the stiff sidewalls and low rolling resistance are features to help accommodate that. That is why there can be a fairly noticeable range reduction if you opt for cheaper tires.
Did anyone mention a cheaper tire? The Michelin Energy Saver is available in a 235/50/18 for about $250/ea. That size has a higher load rating than the OEM tire.
