joenew61

Thanks...Makes sense on the tires. I was just hoping that having the 19" vs 18" was more about appearance than ride, cuz I prefer a softer ride, and they don't sell the 450H up here without the 19" wheels.

On the MPG - I was really just trying to get a general comparison on the 350 vs the 450H, not so much the tires. I know the tires will have some impact, but since I would be looking at the 350 with 18" and the 450H with 19", the data you gave me is perfect!

4 more MPG on the highway, and 9+ more around town - close to EPA estimates..... While it would be a long payback, since I plan on driving the car at least 100k miles (at around 12k per year), and gas prices will probably be approaching $6 a gallon by the end of that period, I think at worst I would break even on the difference in price.

I can be a good global citizen AND it won't cost me anything.

One other question, if I may - road noise and engine noise at highway acceleration/cruise on the 450H with 19" vs 350 with 18" - are they pretty comparable?

markrivers

[QUOTE=joenew61;7005450

One other question, if I may - road noise and engine noise at highway acceleration/cruise on the 450H with 19" vs 350 with 18" - are they pretty comparable?[/QUOTE]

From the start, the RX has fewer road noise compared to the competition.
Thanks to a good cabin sound proofing.
Now, with regards to tires, i have to say it depends on the brand. and the tire pressure.
a Bridgestone will have more noise compared to a Michellin or Dunlop.
that's just my experience.

GRPFAN

Not if that's so like my Goldwing touring cycle Bridgestone tires, Bridgestone will wear much better.

2011RX350

I would love to trade the 19s from my new 2011 CPO RX with 12,000 miles on them but realize it its hard to find simeone wanting to make that trade.

GoHuskers

I will trade your 19" with my 18" on the 350 BUT we live 1000+ miles away. I love the 19". I pay for the look though.

At speed both the 350 and 450h are very quiet. I would say 'Comparable' in term of quietness. However, at the stop/redlight/parking/coasting down the stretch when the foot is OFF the pedal the 450h has NO competitor. It is just dead quiet since the engine is off. I also think my 450h is sealed better than my 350.

joenew61

I'm curious about the ICE cycle on the 450h. If the car is warmed up, AND the battery doesn't need charge, does the ICE actually shut off on the highway at speed if the gas pedal is not engaged or is engaged so lightly as to not need the torque - e.g. in the case of coasting downhill?

Also, does it use both electiric and gas engines when moderate pedal is applied at highway speeds?

I'm trying to understand how it is that the highway MPG is higher than on the 350, and if the same kind of smart hybrid driving that leads to higher MPG in city driving can lead to higher MPG on the highway.

BertL

On my 400h (previous hybrid gen to existing 450h), gas engine does not typically shut off "at highway speeds", even when coasting -- over some number of MPH, gas always is on even if battery indication is it has a full charge. On the other hand, if I'm in stop and go traffic, gas engine will sometimes be off ... that's how one gets great mileage out of this vehicle. While I'm happy I no longer live with lots of stop-and-go traffic, this car really comes into it's own in it.

..and yes, the car can use gas plus electric at the same time and if you have AWD, both electrics and gas will engage together if needed. e.g. this car is GREAT at acceleration on freeway on-ramps, and the AWD beats the socks off the non-hybrid version and FWD four that reason.

GoHuskers

At highway speed, even on a flat surface, the gas engine will be ALWAYS running while the battery helps powering the wheels (it's just on and off but more off than on).

Even when you are doing 80 MPH and you are on the top of the hill, let go off the gas pedal and the Engine will shut off. However, if you touch the gas pedal even slightly the gas engine will come to live.

joenew61

Thanks for the info. If the gas engine stays on, then it must be that the HP coming from the electric side must supplement the HPcoming from the ICE in order to reduce the fuel needed to cruise at highway speeds.

JimH2

I believe the break-even difference in cost would definitely be under 100K when one looks at the estimated rise in gasoline cost within the next 8 years--more likely near 80K miles.

joenew61

Right - around 80k, assuming 5-6% annual increase in gas prices, and IF the MPG advantage is 7-8 over the 350. I just haven't been able to convince myself that the difference in combined mileage will approach those levels, especially on the highway part of the equation. I just don't see where the pickup comes from.

SteveCraig

Our '10 has 18" OEM 5 spoke wheels running 235/60-18 tires(141mm sidewall). I just put 4 new Blizzaks on last week.
Recently bought a very nice set of 4 - 19" OEM 7 spoke wheels & planning on new Summer tires next Spring. OEM rubber size will be 235/55-19(130mm sidewall).

With a sidewall difference of less than 1/2"(11mm), will the ride be noticeably harsher ?
We live in an area where road maintenance can be crude at best. Love the ride now on the 18's.

JLRX

does RIM (larger) offer any advantages when driving in winter conditions?

and what is the largest RIM size that can be used for a 450h?

RX330inFL

No, not particularly better. Narrower tires are actually better in the snow.

http://blog.tirerack.com/blog/hunter...ter-for-winter

The smaller 18" also lends itself better for installing chains should the need arise.

oohpapi44

iTrader: (1)

Larger (19 vs 18) doesn't necessarily mean narrower though. 18x8 is going to have the same contact patch as 19x8 if tire size was same.

Really is going to come down to tire size in the end. Agree that narrower makes sense to be better in winter. I've never noticed any difference in 18 vs 19 in snow in any vehicle i've ever driven and doubt that anyone asking this specific question would either.

OP, believe his s/n is Brendan999 and has just put some 22's on his RX450 and has a review of their performance. But if you mean widest, I have no idea.